CINXE.COM
Standards & Measurements | NIST
<!DOCTYPE html> <html lang="en" dir="ltr" prefix="content: http://purl.org/rss/1.0/modules/content/ dc: http://purl.org/dc/terms/ foaf: http://xmlns.com/foaf/0.1/ og: http://ogp.me/ns# rdfs: http://www.w3.org/2000/01/rdf-schema# schema: http://schema.org/ sioc: http://rdfs.org/sioc/ns# sioct: http://rdfs.org/sioc/types# skos: http://www.w3.org/2004/02/skos/core# xsd: http://www.w3.org/2001/XMLSchema# "> <head><script type="text/javascript" src="/_static/js/bundle-playback.js?v=HxkREWBo" charset="utf-8"></script> <script type="text/javascript" src="/_static/js/wombat.js?v=txqj7nKC" charset="utf-8"></script> <script>window.RufflePlayer=window.RufflePlayer||{};window.RufflePlayer.config={"autoplay":"on","unmuteOverlay":"hidden"};</script> <script type="text/javascript" src="/_static/js/ruffle/ruffle.js"></script> <script type="text/javascript"> __wm.init("https://web.archive.org/web"); __wm.wombat("https://www.nist.gov/services-resources/standards-and-measurements","20240226172038","https://web.archive.org/","web","/_static/", "1708968038"); </script> <link rel="stylesheet" type="text/css" href="/_static/css/banner-styles.css?v=S1zqJCYt" /> <link rel="stylesheet" type="text/css" href="/_static/css/iconochive.css?v=3PDvdIFv" /> <!-- End Wayback Rewrite JS Include --> <meta charset="utf-8"/><script type="text/javascript">(window.NREUM||(NREUM={})).init={ajax:{deny_list:["bam.nr-data.net"]}};(window.NREUM||(NREUM={})).loader_config={licenseKey:"37b7ccb661",applicationID:"1089704227"};;/*! For license information please see nr-loader-rum-1.252.0.min.js.LICENSE.txt */ (()=>{var e,t,r={234:(e,t,r)=>{"use strict";r.d(t,{P_:()=>v,Mt:()=>b,C5:()=>s,DL:()=>w,OP:()=>S,lF:()=>T,Yu:()=>x,Dg:()=>m,CX:()=>c,GE:()=>_,sU:()=>R});var n=r(8632),i=r(9567);const o={beacon:n.ce.beacon,errorBeacon:n.ce.errorBeacon,licenseKey:void 0,applicationID:void 0,sa:void 0,queueTime:void 0,applicationTime:void 0,ttGuid:void 0,user:void 0,account:void 0,product:void 0,extra:void 0,jsAttributes:{},userAttributes:void 0,atts:void 0,transactionName:void 0,tNamePlain:void 0},a={};function s(e){if(!e)throw new Error("All info objects require an agent identifier!");if(!a[e])throw new Error("Info for ".concat(e," was never set"));return a[e]}function c(e,t){if(!e)throw new Error("All info objects require an agent identifier!");a[e]=(0,i.D)(t,o);const r=(0,n.ek)(e);r&&(r.info=a[e])}const u=e=>{if(!e||"string"!=typeof e)return!1;try{document.createDocumentFragment().querySelector(e)}catch{return!1}return!0};var d=r(7056),l=r(50);const f="[data-nr-mask]",g=()=>{const e={mask_selector:"*",block_selector:"[data-nr-block]",mask_input_options:{color:!1,date:!1,"datetime-local":!1,email:!1,month:!1,number:!1,range:!1,search:!1,tel:!1,text:!1,time:!1,url:!1,week:!1,textarea:!1,select:!1,password:!0}};return{feature_flags:[],proxy:{assets:void 0,beacon:void 0},privacy:{cookies_enabled:!0},ajax:{deny_list:void 0,block_internal:!0,enabled:!0,harvestTimeSeconds:10,autoStart:!0},distributed_tracing:{enabled:void 0,exclude_newrelic_header:void 0,cors_use_newrelic_header:void 0,cors_use_tracecontext_headers:void 0,allowed_origins:void 0},session:{domain:void 0,expiresMs:d.oD,inactiveMs:d.Hb},ssl:void 0,obfuscate:void 0,jserrors:{enabled:!0,harvestTimeSeconds:10,autoStart:!0},metrics:{enabled:!0,autoStart:!0},page_action:{enabled:!0,harvestTimeSeconds:30,autoStart:!0},page_view_event:{enabled:!0,autoStart:!0},page_view_timing:{enabled:!0,harvestTimeSeconds:30,long_task:!1,autoStart:!0},session_trace:{enabled:!0,harvestTimeSeconds:10,autoStart:!0},harvest:{tooManyRequestsDelay:60},session_replay:{autoStart:!0,enabled:!1,harvestTimeSeconds:60,sampling_rate:10,error_sampling_rate:100,collect_fonts:!1,inline_images:!1,inline_stylesheet:!0,mask_all_inputs:!0,get mask_text_selector(){return e.mask_selector},set mask_text_selector(t){u(t)?e.mask_selector="".concat(t,",").concat(f):""===t||null===t?e.mask_selector=f:(0,l.Z)("An invalid session_replay.mask_selector was provided. '*' will be used.",t)},get block_class(){return"nr-block"},get ignore_class(){return"nr-ignore"},get mask_text_class(){return"nr-mask"},get block_selector(){return e.block_selector},set block_selector(t){u(t)?e.block_selector+=",".concat(t):""!==t&&(0,l.Z)("An invalid session_replay.block_selector was provided and will not be used",t)},get mask_input_options(){return e.mask_input_options},set mask_input_options(t){t&&"object"==typeof t?e.mask_input_options={...t,password:!0}:(0,l.Z)("An invalid session_replay.mask_input_option was provided and will not be used",t)}},spa:{enabled:!0,harvestTimeSeconds:10,autoStart:!0}}},p={},h="All configuration objects require an agent identifier!";function v(e){if(!e)throw new Error(h);if(!p[e])throw new Error("Configuration for ".concat(e," was never set"));return p[e]}function m(e,t){if(!e)throw new Error(h);p[e]=(0,i.D)(t,g());const r=(0,n.ek)(e);r&&(r.init=p[e])}function b(e,t){if(!e)throw new Error(h);var r=v(e);if(r){for(var n=t.split("."),i=0;i<n.length-1;i++)if("object"!=typeof(r=r[n[i]]))return;r=r[n[n.length-1]]}return r}const y={accountID:void 0,trustKey:void 0,agentID:void 0,licenseKey:void 0,applicationID:void 0,xpid:void 0},A={};function w(e){if(!e)throw new Error("All loader-config objects require an agent identifier!");if(!A[e])throw new Error("LoaderConfig for ".concat(e," was never set"));return A[e]}function _(e,t){if(!e)throw new Error("All loader-config objects require an agent identifier!");A[e]=(0,i.D)(t,y);const r=(0,n.ek)(e);r&&(r.loader_config=A[e])}const x=(0,n.mF)().o;var E=r(385),D=r(6818);const k={buildEnv:D.Re,customTransaction:void 0,disabled:!1,distMethod:D.gF,isolatedBacklog:!1,loaderType:void 0,maxBytes:3e4,offset:Math.floor(E._A?.performance?.timeOrigin||E._A?.performance?.timing?.navigationStart||Date.now()),onerror:void 0,origin:""+E._A.location,ptid:void 0,releaseIds:{},session:void 0,xhrWrappable:"function"==typeof E._A.XMLHttpRequest?.prototype?.addEventListener,version:D.q4,denyList:void 0},j={};function S(e){if(!e)throw new Error("All runtime objects require an agent identifier!");if(!j[e])throw new Error("Runtime for ".concat(e," was never set"));return j[e]}function R(e,t){if(!e)throw new Error("All runtime objects require an agent identifier!");j[e]=(0,i.D)(t,k);const r=(0,n.ek)(e);r&&(r.runtime=j[e])}function T(e){return function(e){try{const t=s(e);return!!t.licenseKey&&!!t.errorBeacon&&!!t.applicationID}catch(e){return!1}}(e)}},9567:(e,t,r)=>{"use strict";r.d(t,{D:()=>i});var n=r(50);function i(e,t){try{if(!e||"object"!=typeof e)return(0,n.Z)("Setting a Configurable requires an object as input");if(!t||"object"!=typeof t)return(0,n.Z)("Setting a Configurable requires a model to set its initial properties");const r=Object.create(Object.getPrototypeOf(t),Object.getOwnPropertyDescriptors(t)),o=0===Object.keys(r).length?e:r;for(let a in o)if(void 0!==e[a])try{Array.isArray(e[a])&&Array.isArray(t[a])?r[a]=Array.from(new Set([...e[a],...t[a]])):"object"==typeof e[a]&&"object"==typeof t[a]?r[a]=i(e[a],t[a]):r[a]=e[a]}catch(e){(0,n.Z)("An error occurred while setting a property of a Configurable",e)}return r}catch(e){(0,n.Z)("An error occured while setting a Configurable",e)}}},6818:(e,t,r)=>{"use strict";r.d(t,{Re:()=>i,gF:()=>o,q4:()=>n});const n="1.252.0",i="PROD",o="CDN"},385:(e,t,r)=>{"use strict";r.d(t,{Nk:()=>d,Tt:()=>s,_A:()=>o,cv:()=>l,iS:()=>a,il:()=>n,ux:()=>c,v6:()=>i,w1:()=>u});const n="undefined"!=typeof window&&!!window.document,i="undefined"!=typeof WorkerGlobalScope&&("undefined"!=typeof self&&self instanceof WorkerGlobalScope&&self.navigator instanceof WorkerNavigator||"undefined"!=typeof globalThis&&globalThis instanceof WorkerGlobalScope&&globalThis.navigator instanceof WorkerNavigator),o=n?window:"undefined"!=typeof WorkerGlobalScope&&("undefined"!=typeof self&&self instanceof WorkerGlobalScope&&self||"undefined"!=typeof globalThis&&globalThis instanceof WorkerGlobalScope&&globalThis),a=Boolean("hidden"===o?.document?.visibilityState),s=/iPad|iPhone|iPod/.test(o.navigator?.userAgent),c=s&&"undefined"==typeof SharedWorker,u=((()=>{const e=o.navigator?.userAgent?.match(/Firefox[/\s](\d+\.\d+)/);Array.isArray(e)&&e.length>=2&&e[1]})(),Boolean(n&&window.document.documentMode)),d=!!o.navigator?.sendBeacon,l=Math.floor(o?.performance?.timeOrigin||o?.performance?.timing?.navigationStart||Date.now())},1117:(e,t,r)=>{"use strict";r.d(t,{w:()=>o});var n=r(50);const i={agentIdentifier:"",ee:void 0};class o{constructor(e){try{if("object"!=typeof e)return(0,n.Z)("shared context requires an object as input");this.sharedContext={},Object.assign(this.sharedContext,i),Object.entries(e).forEach((e=>{let[t,r]=e;Object.keys(i).includes(t)&&(this.sharedContext[t]=r)}))}catch(e){(0,n.Z)("An error occured while setting SharedContext",e)}}}},8e3:(e,t,r)=>{"use strict";r.d(t,{L:()=>d,R:()=>c});var n=r(8325),i=r(1284),o=r(4322),a=r(3325);const s={};function c(e,t){const r={staged:!1,priority:a.p[t]||0};u(e),s[e].get(t)||s[e].set(t,r)}function u(e){e&&(s[e]||(s[e]=new Map))}function d(){let e=arguments.length>0&&void 0!==arguments[0]?arguments[0]:"",t=arguments.length>1&&void 0!==arguments[1]?arguments[1]:"feature",r=arguments.length>2&&void 0!==arguments[2]&&arguments[2];if(u(e),!e||!s[e].get(t)||r)return c(t);s[e].get(t).staged=!0;const a=[...s[e]];function c(t){const r=e?n.ee.get(e):n.ee,a=o.X.handlers;if(r.backlog&&a){var s=r.backlog[t],c=a[t];if(c){for(var u=0;s&&u<s.length;++u)l(s[u],c);(0,i.D)(c,(function(e,t){(0,i.D)(t,(function(t,r){r[0].on(e,r[1])}))}))}delete a[t],r.backlog[t]=null,r.emit("drain-"+t,[])}}a.every((e=>{let[t,r]=e;return r.staged}))&&(a.sort(((e,t)=>e[1].priority-t[1].priority)),a.forEach((t=>{let[r]=t;s[e].delete(r),c(r)})))}function l(e,t){var r=e[1];(0,i.D)(t[r],(function(t,r){var n=e[0];if(r[0]===n){var i=r[1],o=e[3],a=e[2];i.apply(o,a)}}))}},8325:(e,t,r)=>{"use strict";r.d(t,{A:()=>c,ee:()=>u});var n=r(8632),i=r(2210),o=r(234);class a{constructor(e){this.contextId=e}}var s=r(3117);const c="nr@context:".concat(s.a),u=function e(t,r){var n={},s={},d={},f=!1;try{f=16===r.length&&(0,o.OP)(r).isolatedBacklog}catch(e){}var g={on:h,addEventListener:h,removeEventListener:function(e,t){var r=n[e];if(!r)return;for(var i=0;i<r.length;i++)r[i]===t&&r.splice(i,1)},emit:function(e,r,n,i,o){!1!==o&&(o=!0);if(u.aborted&&!i)return;t&&o&&t.emit(e,r,n);for(var a=p(n),c=v(e),d=c.length,l=0;l<d;l++)c[l].apply(a,r);var f=b()[s[e]];f&&f.push([g,e,r,a]);return a},get:m,listeners:v,context:p,buffer:function(e,t){const r=b();if(t=t||"feature",g.aborted)return;Object.entries(e||{}).forEach((e=>{let[n,i]=e;s[i]=t,t in r||(r[t]=[])}))},abort:l,aborted:!1,isBuffering:function(e){return!!b()[s[e]]},debugId:r,backlog:f?{}:t&&"object"==typeof t.backlog?t.backlog:{}};return g;function p(e){return e&&e instanceof a?e:e?(0,i.X)(e,c,(()=>new a(c))):new a(c)}function h(e,t){n[e]=v(e).concat(t)}function v(e){return n[e]||[]}function m(t){return d[t]=d[t]||e(g,t)}function b(){return g.backlog}}(void 0,"globalEE"),d=(0,n.fP)();function l(){u.aborted=!0,Object.keys(u.backlog).forEach((e=>{delete u.backlog[e]}))}d.ee||(d.ee=u)},5546:(e,t,r)=>{"use strict";r.d(t,{E:()=>n,p:()=>i});var n=r(8325).ee.get("handle");function i(e,t,r,i,o){o?(o.buffer([e],i),o.emit(e,t,r)):(n.buffer([e],i),n.emit(e,t,r))}},4322:(e,t,r)=>{"use strict";r.d(t,{X:()=>o});var n=r(5546);o.on=a;var i=o.handlers={};function o(e,t,r,o){a(o||n.E,i,e,t,r)}function a(e,t,r,i,o){o||(o="feature"),e||(e=n.E);var a=t[o]=t[o]||{};(a[r]=a[r]||[]).push([e,i])}},3239:(e,t,r)=>{"use strict";r.d(t,{bP:()=>s,iz:()=>c,m$:()=>a});var n=r(385);let i=!1,o=!1;try{const e={get passive(){return i=!0,!1},get signal(){return o=!0,!1}};n._A.addEventListener("test",null,e),n._A.removeEventListener("test",null,e)}catch(e){}function a(e,t){return i||o?{capture:!!e,passive:i,signal:t}:!!e}function s(e,t){let r=arguments.length>2&&void 0!==arguments[2]&&arguments[2],n=arguments.length>3?arguments[3]:void 0;window.addEventListener(e,t,a(r,n))}function c(e,t){let r=arguments.length>2&&void 0!==arguments[2]&&arguments[2],n=arguments.length>3?arguments[3]:void 0;document.addEventListener(e,t,a(r,n))}},3117:(e,t,r)=>{"use strict";r.d(t,{a:()=>n});const n=(0,r(4402).Rl)()},4402:(e,t,r)=>{"use strict";r.d(t,{Rl:()=>a,ky:()=>s});var n=r(385);const i="xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";function o(e,t){return e?15&e[t]:16*Math.random()|0}function a(){const e=n._A?.crypto||n._A?.msCrypto;let t,r=0;return e&&e.getRandomValues&&(t=e.getRandomValues(new Uint8Array(30))),i.split("").map((e=>"x"===e?o(t,r++).toString(16):"y"===e?(3&o()|8).toString(16):e)).join("")}function s(e){const t=n._A?.crypto||n._A?.msCrypto;let r,i=0;t&&t.getRandomValues&&(r=t.getRandomValues(new Uint8Array(e)));const a=[];for(var s=0;s<e;s++)a.push(o(r,i++).toString(16));return a.join("")}},7056:(e,t,r)=>{"use strict";r.d(t,{Bq:()=>n,Hb:()=>o,IK:()=>c,oD:()=>i,uT:()=>s,wO:()=>a});const n="NRBA",i=144e5,o=18e5,a={PAUSE:"session-pause",RESET:"session-reset",RESUME:"session-resume",UPDATE:"session-update"},s={SAME_TAB:"same-tab",CROSS_TAB:"cross-tab"},c={OFF:0,FULL:1,ERROR:2}},7894:(e,t,r)=>{"use strict";function n(){return Math.round(performance.now())}r.d(t,{z:()=>n})},50:(e,t,r)=>{"use strict";function n(e,t){"function"==typeof console.warn&&(console.warn("New Relic: ".concat(e)),t&&console.warn(t))}r.d(t,{Z:()=>n})},2825:(e,t,r)=>{"use strict";r.d(t,{N:()=>d,T:()=>l});var n=r(8325),i=r(5546),o=r(3325),a=r(385);const s="newrelic";const c={stn:[o.D.sessionTrace],err:[o.D.jserrors,o.D.metrics],ins:[o.D.pageAction],spa:[o.D.spa],sr:[o.D.sessionReplay,o.D.sessionTrace]},u=new Set;function d(e,t){const r=n.ee.get(t);e&&"object"==typeof e&&(u.has(t)||(Object.entries(e).forEach((e=>{let[t,n]=e;c[t]?c[t].forEach((e=>{n?(0,i.p)("feat-"+t,[],void 0,e,r):(0,i.p)("block-"+t,[],void 0,e,r),(0,i.p)("rumresp-"+t,[Boolean(n)],void 0,e,r)})):n&&(0,i.p)("feat-"+t,[],void 0,void 0,r),l[t]=Boolean(n)})),Object.keys(c).forEach((e=>{void 0===l[e]&&(c[e]?.forEach((t=>(0,i.p)("rumresp-"+e,[!1],void 0,t,r))),l[e]=!1)})),u.add(t),function(){let e=arguments.length>0&&void 0!==arguments[0]?arguments[0]:{};try{a._A.dispatchEvent(new CustomEvent(s,{detail:e}))}catch(e){}}({loaded:!0})))}const l={}},2210:(e,t,r)=>{"use strict";r.d(t,{X:()=>i});var n=Object.prototype.hasOwnProperty;function i(e,t,r){if(n.call(e,t))return e[t];var i=r();if(Object.defineProperty&&Object.keys)try{return Object.defineProperty(e,t,{value:i,writable:!0,enumerable:!1}),i}catch(e){}return e[t]=i,i}},1284:(e,t,r)=>{"use strict";r.d(t,{D:()=>n});const n=(e,t)=>Object.entries(e||{}).map((e=>{let[r,n]=e;return t(r,n)}))},4351:(e,t,r)=>{"use strict";r.d(t,{P:()=>o});var n=r(8325);const i=()=>{const e=new WeakSet;return(t,r)=>{if("object"==typeof r&&null!==r){if(e.has(r))return;e.add(r)}return r}};function o(e){try{return JSON.stringify(e,i())}catch(e){try{n.ee.emit("internal-error",[e])}catch(e){}}}},3960:(e,t,r)=>{"use strict";r.d(t,{KB:()=>a,b2:()=>o});var n=r(3239);function i(){return"undefined"==typeof document||"complete"===document.readyState}function o(e,t){if(i())return e();(0,n.bP)("load",e,t)}function a(e){if(i())return e();(0,n.iz)("DOMContentLoaded",e)}},8632:(e,t,r)=>{"use strict";r.d(t,{EZ:()=>d,ce:()=>o,ek:()=>u,fP:()=>a,gG:()=>l,h5:()=>c,mF:()=>s});var n=r(7894),i=r(385);const o={beacon:"bam.nr-data.net",errorBeacon:"bam.nr-data.net"};function a(){return i._A.NREUM||(i._A.NREUM={}),void 0===i._A.newrelic&&(i._A.newrelic=i._A.NREUM),i._A.NREUM}function s(){let e=a();return e.o||(e.o={ST:i._A.setTimeout,SI:i._A.setImmediate,CT:i._A.clearTimeout,XHR:i._A.XMLHttpRequest,REQ:i._A.Request,EV:i._A.Event,PR:i._A.Promise,MO:i._A.MutationObserver,FETCH:i._A.fetch}),e}function c(e,t){let r=a();r.initializedAgents??={},t.initializedAt={ms:(0,n.z)(),date:new Date},r.initializedAgents[e]=t}function u(e){let t=a();return t.initializedAgents?.[e]}function d(e,t){a()[e]=t}function l(){return function(){let e=a();const t=e.info||{};e.info={beacon:o.beacon,errorBeacon:o.errorBeacon,...t}}(),function(){let e=a();const t=e.init||{};e.init={...t}}(),s(),function(){let e=a();const t=e.loader_config||{};e.loader_config={...t}}(),a()}},7956:(e,t,r)=>{"use strict";r.d(t,{N:()=>i});var n=r(3239);function i(e){let t=arguments.length>1&&void 0!==arguments[1]&&arguments[1],r=arguments.length>2?arguments[2]:void 0,i=arguments.length>3?arguments[3]:void 0;(0,n.iz)("visibilitychange",(function(){if(t)return void("hidden"===document.visibilityState&&e());e(document.visibilityState)}),r,i)}},3081:(e,t,r)=>{"use strict";r.d(t,{gF:()=>o,mY:()=>i,t9:()=>n,vz:()=>s,xS:()=>a});const n=r(3325).D.metrics,i="sm",o="cm",a="storeSupportabilityMetrics",s="storeEventMetrics"},7633:(e,t,r)=>{"use strict";r.d(t,{t:()=>n});const n=r(3325).D.pageViewEvent},9251:(e,t,r)=>{"use strict";r.d(t,{t:()=>n});const n=r(3325).D.pageViewTiming},5938:(e,t,r)=>{"use strict";r.d(t,{W:()=>i});var n=r(8325);class i{constructor(e,t,r){this.agentIdentifier=e,this.aggregator=t,this.ee=n.ee.get(e),this.featureName=r,this.blocked=!1}}},7530:(e,t,r)=>{"use strict";r.d(t,{j:()=>b});var n=r(3325),i=r(234),o=r(5546),a=r(8325),s=r(7894),c=r(8e3),u=r(3960),d=r(385),l=r(50),f=r(3081),g=r(8632);function p(){const e=(0,g.gG)();["setErrorHandler","finished","addToTrace","addRelease","addPageAction","setCurrentRouteName","setPageViewName","setCustomAttribute","interaction","noticeError","setUserId","setApplicationVersion","start","recordReplay","pauseReplay"].forEach((t=>{e[t]=function(){for(var r=arguments.length,n=new Array(r),i=0;i<r;i++)n[i]=arguments[i];return function(t){for(var r=arguments.length,n=new Array(r>1?r-1:0),i=1;i<r;i++)n[i-1]=arguments[i];let o=[];return Object.values(e.initializedAgents).forEach((e=>{e.exposed&&e.api[t]&&o.push(e.api[t](...n))})),o.length>1?o:o[0]}(t,...n)}}))}var h=r(2825);const v=e=>{const t=e.startsWith("http");e+="/",r.p=t?e:"https://"+e};let m=!1;function b(e){let t=arguments.length>1&&void 0!==arguments[1]?arguments[1]:{},b=arguments.length>2?arguments[2]:void 0,y=arguments.length>3?arguments[3]:void 0,{init:A,info:w,loader_config:_,runtime:x={loaderType:b},exposed:E=!0}=t;const D=(0,g.gG)();w||(A=D.init,w=D.info,_=D.loader_config),(0,i.Dg)(e.agentIdentifier,A||{}),(0,i.GE)(e.agentIdentifier,_||{}),w.jsAttributes??={},d.v6&&(w.jsAttributes.isWorker=!0),(0,i.CX)(e.agentIdentifier,w);const k=(0,i.P_)(e.agentIdentifier),j=[w.beacon,w.errorBeacon];m||(k.proxy.assets&&(v(k.proxy.assets),j.push(k.proxy.assets)),k.proxy.beacon&&j.push(k.proxy.beacon),p(),(0,g.EZ)("activatedFeatures",h.T)),x.denyList=[...k.ajax.deny_list||[],...k.ajax.block_internal?j:[]],(0,i.sU)(e.agentIdentifier,x),void 0===e.api&&(e.api=function(e,t){t||(0,c.R)(e,"api");const g={};var p=a.ee.get(e),h=p.get("tracer"),v="api-",m=v+"ixn-";function b(t,r,n,o){const a=(0,i.C5)(e);return null===r?delete a.jsAttributes[t]:(0,i.CX)(e,{...a,jsAttributes:{...a.jsAttributes,[t]:r}}),w(v,n,!0,o||null===r?"session":void 0)(t,r)}function y(){}["setErrorHandler","finished","addToTrace","addRelease"].forEach((e=>{g[e]=w(v,e,!0,"api")})),g.addPageAction=w(v,"addPageAction",!0,n.D.pageAction),g.setCurrentRouteName=w(v,"routeName",!0,n.D.spa),g.setPageViewName=function(t,r){if("string"==typeof t)return"/"!==t.charAt(0)&&(t="/"+t),(0,i.OP)(e).customTransaction=(r||"https://web.archive.org/web/20240226172038/http://custom.transaction")+t,w(v,"setPageViewName",!0)()},g.setCustomAttribute=function(e,t){let r=arguments.length>2&&void 0!==arguments[2]&&arguments[2];if("string"==typeof e){if(["string","number","boolean"].includes(typeof t)||null===t)return b(e,t,"setCustomAttribute",r);(0,l.Z)("Failed to execute setCustomAttribute.\nNon-null value must be a string, number or boolean type, but a type of <".concat(typeof t,"> was provided."))}else(0,l.Z)("Failed to execute setCustomAttribute.\nName must be a string type, but a type of <".concat(typeof e,"> was provided."))},g.setUserId=function(e){if("string"==typeof e||null===e)return b("enduser.id",e,"setUserId",!0);(0,l.Z)("Failed to execute setUserId.\nNon-null value must be a string type, but a type of <".concat(typeof e,"> was provided."))},g.setApplicationVersion=function(e){if("string"==typeof e||null===e)return b("application.version",e,"setApplicationVersion",!1);(0,l.Z)("Failed to execute setApplicationVersion. Expected <String | null>, but got <".concat(typeof e,">."))},g.start=e=>{try{const t=e?"defined":"undefined";(0,o.p)(f.xS,["API/start/".concat(t,"/called")],void 0,n.D.metrics,p);const r=Object.values(n.D);if(void 0===e)e=r;else{if((e=Array.isArray(e)&&e.length?e:[e]).some((e=>!r.includes(e))))return(0,l.Z)("Invalid feature name supplied. Acceptable feature names are: ".concat(r));e.includes(n.D.pageViewEvent)||e.push(n.D.pageViewEvent)}e.forEach((e=>{p.emit("".concat(e,"-opt-in"))}))}catch(e){(0,l.Z)("An unexpected issue occurred",e)}},g.recordReplay=function(){(0,o.p)(f.xS,["API/recordReplay/called"],void 0,n.D.metrics,p),(0,o.p)("recordReplay",[],void 0,n.D.sessionReplay,p)},g.pauseReplay=function(){(0,o.p)(f.xS,["API/pauseReplay/called"],void 0,n.D.metrics,p),(0,o.p)("pauseReplay",[],void 0,n.D.sessionReplay,p)},g.interaction=function(){return(new y).get()};var A=y.prototype={createTracer:function(e,t){var r={},i=this,a="function"==typeof t;return(0,o.p)(f.xS,["API/createTracer/called"],void 0,n.D.metrics,p),(0,o.p)(m+"tracer",[(0,s.z)(),e,r],i,n.D.spa,p),function(){if(h.emit((a?"":"no-")+"fn-start",[(0,s.z)(),i,a],r),a)try{return t.apply(this,arguments)}catch(e){throw h.emit("fn-err",[arguments,this,e],r),e}finally{h.emit("fn-end",[(0,s.z)()],r)}}}};function w(e,t,r,i){return function(){return(0,o.p)(f.xS,["API/"+t+"/called"],void 0,n.D.metrics,p),i&&(0,o.p)(e+t,[(0,s.z)(),...arguments],r?null:this,i,p),r?void 0:this}}function _(){r.e(75).then(r.bind(r,7438)).then((t=>{let{setAPI:r}=t;r(e),(0,c.L)(e,"api")})).catch((()=>{(0,l.Z)("Downloading runtime APIs failed..."),(0,c.L)(e,"api",!0)}))}return["actionText","setName","setAttribute","save","ignore","onEnd","getContext","end","get"].forEach((e=>{A[e]=w(m,e,void 0,n.D.spa)})),g.noticeError=function(e,t){"string"==typeof e&&(e=new Error(e)),(0,o.p)(f.xS,["API/noticeError/called"],void 0,n.D.metrics,p),(0,o.p)("err",[e,(0,s.z)(),!1,t],void 0,n.D.jserrors,p)},d.il?(0,u.b2)((()=>_()),!0):_(),g}(e.agentIdentifier,y)),void 0===e.exposed&&(e.exposed=E),m=!0}},1926:(e,t,r)=>{r.nc=(()=>{try{return document?.currentScript?.nonce}catch(e){}return""})()},3325:(e,t,r)=>{"use strict";r.d(t,{D:()=>n,p:()=>i});const n={ajax:"ajax",jserrors:"jserrors",metrics:"metrics",pageAction:"page_action",pageViewEvent:"page_view_event",pageViewTiming:"page_view_timing",sessionReplay:"session_replay",sessionTrace:"session_trace",spa:"spa"},i={[n.pageViewEvent]:1,[n.pageViewTiming]:2,[n.metrics]:3,[n.jserrors]:4,[n.ajax]:5,[n.sessionTrace]:6,[n.pageAction]:7,[n.spa]:8,[n.sessionReplay]:9}}},n={};function i(e){var t=n[e];if(void 0!==t)return t.exports;var o=n[e]={exports:{}};return r[e](o,o.exports,i),o.exports}i.m=r,i.d=(e,t)=>{for(var r in t)i.o(t,r)&&!i.o(e,r)&&Object.defineProperty(e,r,{enumerable:!0,get:t[r]})},i.f={},i.e=e=>Promise.all(Object.keys(i.f).reduce(((t,r)=>(i.f[r](e,t),t)),[])),i.u=e=>"nr-rum-1.252.0.min.js",i.o=(e,t)=>Object.prototype.hasOwnProperty.call(e,t),e={},t="NRBA-1.252.0.PROD:",i.l=(r,n,o,a)=>{if(e[r])e[r].push(n);else{var s,c;if(void 0!==o)for(var u=document.getElementsByTagName("script"),d=0;d<u.length;d++){var l=u[d];if(l.getAttribute("src")==r||l.getAttribute("data-webpack")==t+o){s=l;break}}if(!s){c=!0;var f={75:"sha512-85KXSsv643MTRPulZfmcwj8IKIbJeT9JfNpsSBckCZNUr+o/ILbmpOISx04Ol69WzHRZplUy/y2FaJ3KUChaTw=="};(s=document.createElement("script")).charset="utf-8",s.timeout=120,i.nc&&s.setAttribute("nonce",i.nc),s.setAttribute("data-webpack",t+o),s.src=r,0!==s.src.indexOf(window.location.origin+"/")&&(s.crossOrigin="anonymous"),f[a]&&(s.integrity=f[a])}e[r]=[n];var g=(t,n)=>{s.onerror=s.onload=null,clearTimeout(p);var i=e[r];if(delete e[r],s.parentNode&&s.parentNode.removeChild(s),i&&i.forEach((e=>e(n))),t)return t(n)},p=setTimeout(g.bind(null,void 0,{type:"timeout",target:s}),12e4);s.onerror=g.bind(null,s.onerror),s.onload=g.bind(null,s.onload),c&&document.head.appendChild(s)}},i.r=e=>{"undefined"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:"Module"}),Object.defineProperty(e,"__esModule",{value:!0})},i.p="https://web.archive.org/web/20240226172038/https://js-agent.newrelic.com/",(()=>{var e={50:0,832:0};i.f.j=(t,r)=>{var n=i.o(e,t)?e[t]:void 0;if(0!==n)if(n)r.push(n[2]);else{var o=new Promise(((r,i)=>n=e[t]=[r,i]));r.push(n[2]=o);var a=i.p+i.u(t),s=new Error;i.l(a,(r=>{if(i.o(e,t)&&(0!==(n=e[t])&&(e[t]=void 0),n)){var o=r&&("load"===r.type?"missing":r.type),a=r&&r.target&&r.target.src;s.message="Loading chunk "+t+" failed.\n("+o+": "+a+")",s.name="ChunkLoadError",s.type=o,s.request=a,n[1](s)}}),"chunk-"+t,t)}};var t=(t,r)=>{var n,o,[a,s,c]=r,u=0;if(a.some((t=>0!==e[t]))){for(n in s)i.o(s,n)&&(i.m[n]=s[n]);if(c)c(i)}for(t&&t(r);u<a.length;u++)o=a[u],i.o(e,o)&&e[o]&&e[o][0](),e[o]=0},r=self["webpackChunk:NRBA-1.252.0.PROD"]=self["webpackChunk:NRBA-1.252.0.PROD"]||[];r.forEach(t.bind(null,0)),r.push=t.bind(null,r.push.bind(r))})(),(()=>{"use strict";i(1926);var e=i(50);class t{#e(t){for(var r=arguments.length,n=new Array(r>1?r-1:0),i=1;i<r;i++)n[i-1]=arguments[i];if("function"==typeof this.api?.[t])return this.api[t](...n);(0,e.Z)("Call to agent api ".concat(t," failed. The API is not currently initialized."))}addPageAction(e,t){return this.#e("addPageAction",e,t)}setPageViewName(e,t){return this.#e("setPageViewName",e,t)}setCustomAttribute(e,t,r){return this.#e("setCustomAttribute",e,t,r)}noticeError(e,t){return this.#e("noticeError",e,t)}setUserId(e){return this.#e("setUserId",e)}setApplicationVersion(e){return this.#e("setApplicationVersion",e)}setErrorHandler(e){return this.#e("setErrorHandler",e)}finished(e){return this.#e("finished",e)}addRelease(e,t){return this.#e("addRelease",e,t)}start(e){return this.#e("start",e)}recordReplay(){return this.#e("recordReplay")}pauseReplay(){return this.#e("pauseReplay")}addToTrace(e){return this.#e("addToTrace",e)}setCurrentRouteName(e){return this.#e("setCurrentRouteName",e)}interaction(){return this.#e("interaction")}}var r=i(3325),n=i(234);const o=Object.values(r.D);function a(e){const t={};return o.forEach((r=>{t[r]=function(e,t){return!1!==(0,n.Mt)(t,"".concat(e,".enabled"))}(r,e)})),t}var s=i(7530);var c=i(8e3),u=i(5938),d=i(3960),l=i(385);class f extends u.W{constructor(e,t,r){let i=!(arguments.length>3&&void 0!==arguments[3])||arguments[3];super(e,t,r),this.auto=i,this.abortHandler=void 0,this.featAggregate=void 0,this.onAggregateImported=void 0,!1===(0,n.Mt)(this.agentIdentifier,"".concat(this.featureName,".autoStart"))&&(this.auto=!1),this.auto&&(0,c.R)(e,r)}importAggregator(){let t=arguments.length>0&&void 0!==arguments[0]?arguments[0]:{};if(this.featAggregate)return;if(!this.auto)return void this.ee.on("".concat(this.featureName,"-opt-in"),(()=>{(0,c.R)(this.agentIdentifier,this.featureName),this.auto=!0,this.importAggregator()}));const r=l.il&&!0===(0,n.Mt)(this.agentIdentifier,"privacy.cookies_enabled");let o;this.onAggregateImported=new Promise((e=>{o=e}));const a=async()=>{let n;try{if(r){const{setupAgentSession:e}=await i.e(75).then(i.bind(i,957));n=e(this.agentIdentifier)}}catch(t){(0,e.Z)("A problem occurred when starting up session manager. This page will not start or extend any session.",t)}try{if(!this.shouldImportAgg(this.featureName,n))return(0,c.L)(this.agentIdentifier,this.featureName),void o(!1);const{lazyFeatureLoader:e}=await i.e(75).then(i.bind(i,8582)),{Aggregate:r}=await e(this.featureName,"aggregate");this.featAggregate=new r(this.agentIdentifier,this.aggregator,t),o(!0)}catch(t){(0,e.Z)("Downloading and initializing ".concat(this.featureName," failed..."),t),this.abortHandler?.(),(0,c.L)(this.agentIdentifier,this.featureName,!0),o(!1)}};l.il?(0,d.b2)((()=>a()),!0):a()}shouldImportAgg(e,t){return e!==r.D.sessionReplay||!!n.Yu.MO&&(!1!==(0,n.Mt)(this.agentIdentifier,"session_trace.enabled")&&(!!t?.isNew||!!t?.state.sessionReplayMode))}}var g=i(7633);class p extends f{static featureName=g.t;constructor(e,t){let r=!(arguments.length>2&&void 0!==arguments[2])||arguments[2];super(e,t,g.t,r),this.importAggregator()}}var h=i(1117),v=i(1284);class m extends h.w{constructor(e){super(e),this.aggregatedData={}}store(e,t,r,n,i){var o=this.getBucket(e,t,r,i);return o.metrics=function(e,t){t||(t={count:0});return t.count+=1,(0,v.D)(e,(function(e,r){t[e]=b(r,t[e])})),t}(n,o.metrics),o}merge(e,t,r,n,i){var o=this.getBucket(e,t,n,i);if(o.metrics){var a=o.metrics;a.count+=r.count,(0,v.D)(r,(function(e,t){if("count"!==e){var n=a[e],i=r[e];i&&!i.c?a[e]=b(i.t,n):a[e]=function(e,t){if(!t)return e;t.c||(t=y(t.t));return t.min=Math.min(e.min,t.min),t.max=Math.max(e.max,t.max),t.t+=e.t,t.sos+=e.sos,t.c+=e.c,t}(i,a[e])}}))}else o.metrics=r}storeMetric(e,t,r,n){var i=this.getBucket(e,t,r);return i.stats=b(n,i.stats),i}getBucket(e,t,r,n){this.aggregatedData[e]||(this.aggregatedData[e]={});var i=this.aggregatedData[e][t];return i||(i=this.aggregatedData[e][t]={params:r||{}},n&&(i.custom=n)),i}get(e,t){return t?this.aggregatedData[e]&&this.aggregatedData[e][t]:this.aggregatedData[e]}take(e){for(var t={},r="",n=!1,i=0;i<e.length;i++)t[r=e[i]]=A(this.aggregatedData[r]),t[r].length&&(n=!0),delete this.aggregatedData[r];return n?t:null}}function b(e,t){return null==e?function(e){e?e.c++:e={c:1};return e}(t):t?(t.c||(t=y(t.t)),t.c+=1,t.t+=e,t.sos+=e*e,e>t.max&&(t.max=e),e<t.min&&(t.min=e),t):{t:e}}function y(e){return{t:e,min:e,max:e,sos:e*e,c:1}}function A(e){return"object"!=typeof e?[]:(0,v.D)(e,w)}function w(e,t){return t}var _=i(8632),x=i(4402),E=i(4351);var D=i(5546),k=i(7956),j=i(3239),S=i(7894),R=i(9251);class T extends f{static featureName=R.t;constructor(e,t){let r=!(arguments.length>2&&void 0!==arguments[2])||arguments[2];super(e,t,R.t,r),l.il&&((0,k.N)((()=>(0,D.p)("docHidden",[(0,S.z)()],void 0,R.t,this.ee)),!0),(0,j.bP)("pagehide",(()=>(0,D.p)("winPagehide",[(0,S.z)()],void 0,R.t,this.ee))),this.importAggregator())}}var I=i(3081);class P extends f{static featureName=I.t9;constructor(e,t){let r=!(arguments.length>2&&void 0!==arguments[2])||arguments[2];super(e,t,I.t9,r),this.importAggregator()}}new class extends t{constructor(t){let r=arguments.length>1&&void 0!==arguments[1]?arguments[1]:(0,x.ky)(16);super(),l._A?(this.agentIdentifier=r,this.sharedAggregator=new m({agentIdentifier:this.agentIdentifier}),this.features={},(0,_.h5)(r,this),this.desiredFeatures=new Set(t.features||[]),this.desiredFeatures.add(p),(0,s.j)(this,t,t.loaderType||"agent"),this.run()):(0,e.Z)("Failed to initial the agent. Could not determine the runtime environment.")}get config(){return{info:(0,n.C5)(this.agentIdentifier),init:(0,n.P_)(this.agentIdentifier),loader_config:(0,n.DL)(this.agentIdentifier),runtime:(0,n.OP)(this.agentIdentifier)}}run(){try{const t=a(this.agentIdentifier),n=[...this.desiredFeatures];n.sort(((e,t)=>r.p[e.featureName]-r.p[t.featureName])),n.forEach((n=>{if(t[n.featureName]||n.featureName===r.D.pageViewEvent){const i=function(e){switch(e){case r.D.ajax:return[r.D.jserrors];case r.D.sessionTrace:return[r.D.ajax,r.D.pageViewEvent];case r.D.sessionReplay:return[r.D.sessionTrace];case r.D.pageViewTiming:return[r.D.pageViewEvent];default:return[]}}(n.featureName);i.every((e=>t[e]))||(0,e.Z)("".concat(n.featureName," is enabled but one or more dependent features has been disabled (").concat((0,E.P)(i),"). This may cause unintended consequences or missing data...")),this.features[n.featureName]=new n(this.agentIdentifier,this.sharedAggregator)}}))}catch(t){(0,e.Z)("Failed to initialize all enabled instrument classes (agent aborted) -",t);for(const e in this.features)this.features[e].abortHandler?.();const r=(0,_.fP)();return delete r.initializedAgents[this.agentIdentifier]?.api,delete r.initializedAgents[this.agentIdentifier]?.features,delete this.sharedAggregator,r.ee?.abort(),delete r.ee?.get(this.agentIdentifier),!1}}}({features:[p,T,P],loaderType:"lite"})})()})();</script> <noscript><style>form.antibot * :not(.antibot-message) { display: none !important; }</style> </noscript><script async src="https://web.archive.org/web/20240226172038js_/https://www.googletagmanager.com/gtag/js?id=G-HEQ0YF2VYL"></script> <script>window.dataLayer = window.dataLayer || [];function gtag(){dataLayer.push(arguments)};gtag("js", new Date());gtag("set", "developer_id.dMDhkMT", true);gtag('set', {'cookie_flags': 'SameSite=None;Secure', 'cookie_domain': 'www.nist.gov'});gtag("config", "G-HEQ0YF2VYL", {"groups":"default","page_placeholder":"PLACEHOLDER_page_location","link_attribution":true,"allow_ad_personalization_signals":false});gtag("config", "UA-33523145-1", {"groups":"default","anonymize_ip":true,"page_placeholder":"PLACEHOLDER_page_path","link_attribution":true,"allow_ad_personalization_signals":false,"custom_map":{"dimension2":"node_title","dimension3":"node_id","dimension7":"content_type"}});gtag("config", "G-CSLL4ZEK4L", {"groups":"default","page_placeholder":"PLACEHOLDER_page_location","link_attribution":true,"allow_ad_personalization_signals":false});gtag("event", "custom", {"node_title":"Standards \u0026amp; Measurements","node_id":"386181","content_type":"Basic page"});</script> <meta name="description" content="Standards allow technology to work seamlessly and establish trust so that markets can operate smoothly. They:"/> <link rel="canonical" href="https://web.archive.org/web/20240226172038/https://www.nist.gov/services-resources/standards-and-measurements"/> <link rel="shortlink" href="https://web.archive.org/web/20240226172038/https://www.nist.gov/node/386181"/> <meta name="citation_title" content="Standards & Measurements | NIST"/> <meta property="og:site_name" content="NIST"/> <meta property="og:type" content="Article"/> <meta property="og:url" content="https://web.archive.org/web/20240226172038/https://www.nist.gov/services-resources/standards-and-measurements"/> <meta property="og:title" content="Standards & Measurements"/> <meta property="og:description" content="Standards allow technology to work seamlessly and establish trust so that markets can operate smoothly. They:"/> <meta property="article:published_time" content="2015-06-22T11:19-04:00"/> <meta property="article:modified_time" content="2022-01-18T10:25-05:00"/> <meta name="dcterms.title" content="Standards & Measurements"/> <meta name="dcterms.description" content="Standards allow technology to work seamlessly and establish trust so that markets can operate smoothly. They:"/> <meta name="dcterms.date" content="2015-06-22T11:19-04:00"/> <meta name="dcterms.type" content="text"/> <meta name="dcterms.format" content="text/html"/> <meta name="dcterms.identifier" content="https://www.nist.gov/services-resources/standards-and-measurements"/> <meta name="dcterms.source" content="NIST"/> <meta name="dcterms.created" content="2015-06-22T11:19-04:00"/> <meta name="dcterms.modified" content="2022-01-18T10:25-05:00"/> <meta name="twitter:card" content="summary_large_image"/> <meta name="twitter:description" content="Standards allow technology to work seamlessly and establish trust so that markets can operate smoothly. They:"/> <meta name="twitter:site" content="NIST"/> <meta name="twitter:title" content="Standards & Measurements"/> <meta name="google-site-verification" content="QMu0ODkER3rN5hLcMLqNVf7e3bkjYsNLTuhqfH48jCA"/> <meta name="Generator" content="Drupal 10 (https://www.drupal.org)"/> <meta name="MobileOptimized" content="width"/> <meta name="HandheldFriendly" content="true"/> <meta name="viewport" content="width=device-width, initial-scale=1.0"/> <meta name="nist_search_modified" class="elastic" content="2022-01-18T10:25:00-05:00"/> <script type="application/ld+json">{ "@context": "https://web.archive.org/web/20240226172038/https://schema.org", "@graph": [ { "@type": "Article", "headline": "Standards \u0026 Measurements | NIST", "description": "Standards allow technology to work seamlessly and establish trust so that markets can operate smoothly. They:", "datePublished": "2015-06-22T11:19-04:00", "dateModified": "2022-01-18T10:25-05:00" } ] }</script> <meta name="nist_search_bundle" class="elastic" content="page"/> <link rel="icon" href="/web/20240226172038im_/https://www.nist.gov/themes/custom/nist_www/favicon.ico" type="image/vnd.microsoft.icon"/> <title>Standards & Measurements | NIST</title> <link rel="stylesheet" media="all" href="/web/20240226172038cs_/https://www.nist.gov/sites/default/files/css/css_yH4FeFOhjNDD-YW6lHos6UT-Z8GpPnxY3OA1G_MIIjE.css?delta=0&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"/> <link rel="stylesheet" media="all" href="/web/20240226172038cs_/https://www.nist.gov/sites/default/files/css/css_6prwlieMvitJqVLptJ59w_NxX2prM0abXhYVoH12prk.css?delta=1&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"/> <link rel="stylesheet" media="print" href="/web/20240226172038cs_/https://www.nist.gov/sites/default/files/css/css_6MuKXqcH69mMwmOSjiD2G_c6UXIqUTZ1TRnur95k7Qk.css?delta=2&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"/> <link rel="stylesheet" media="all" href="/web/20240226172038cs_/https://www.nist.gov/sites/default/files/css/css_Vlb5tKBrTnXBpCoEIEyOWSUGgmDWOgkDFIgemxZcHGg.css?delta=3&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"/> <script src="/web/20240226172038js_/https://www.nist.gov/sites/default/files/js/js_3ssAdmvsW-btol8ydZT2eloQN8l11yuGacOobfI1-_0.js?scope=header&delta=0&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"></script> </head> <body class="node-386181"> <a href="#main-content" class="visually-hidden focusable" data-elastic-exclude> Skip to main content </a> <div class="dialog-off-canvas-main-canvas" data-off-canvas-main-canvas> <!-- nist-index-ignore-start --> <section data-elastic-exclude class="usa-banner" aria-label="Official government website"> <div class="usa-accordion"> <header class="usa-banner__header"> <div class="usa-banner__inner"> <div class="grid-col-auto"> <img class="usa-banner__header-flag" src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/us_flag_small.png" alt="U.S. flag"> </div> <div class="grid-col-fill tablet:grid-col-auto"> <p class="usa-banner__header-text">An official website of the United States government</p> <p class="usa-banner__header-action" aria-hidden="true">Here’s how you know</p> </div> <button class="usa-accordion__button usa-banner__button" aria-expanded="false" aria-controls="gov-banner-default"> <span class="usa-banner__button-text">Here’s how you know</span> </button> </div> </header> <div class="usa-banner__content usa-accordion__content" id="gov-banner-default"> <div class="grid-row grid-gap-lg"> <div class="usa-banner__guidance tablet:grid-col-6"> <img class="usa-banner__icon usa-media-block__img" src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/icon-dot-gov.svg" role="img" alt="" aria-hidden="true"> <div class="usa-media-block__body"> <p> <strong>Official websites use .gov</strong> <br/> A <strong>.gov</strong> website belongs to an official government organization in the United States. </p> </div> </div> <div class="usa-banner__guidance tablet:grid-col-6"> <img class="usa-banner__icon usa-media-block__img" src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/icon-https.svg" role="img" alt="" aria-hidden="true"> <div class="usa-media-block__body"> <p> <strong>Secure .gov websites use HTTPS</strong> <br/> A <strong>lock</strong> ( <span class="icon-lock"> <svg xmlns="http://www.w3.org/2000/svg" width="52" height="64" viewbox="0 0 52 64" class="usa-banner__lock-image" role="img" aria-labelledby="banner-lock-title banner-lock-description" focusable="false"> <title id="banner-lock-title">Lock</title> <desc id="banner-lock-description">A locked padlock</desc><path fill="#000000" fill-rule="evenodd" d="M26 0c10.493 0 19 8.507 19 19v9h3a4 4 0 0 1 4 4v28a4 4 0 0 1-4 4H4a4 4 0 0 1-4-4V32a4 4 0 0 1 4-4h3v-9C7 8.507 15.507 0 26 0zm0 8c-5.979 0-10.843 4.77-10.996 10.712L15 19v9h22v-9c0-6.075-4.925-11-11-11z"/></svg> </span> ) or <strong>https://</strong> means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. </p> </div> </div> </div> </div> </div> </section> <!-- nist-index-ignore-end --> <div data-elastic-exclude> <!-- nist-index-ignore-start --> <div class="nist-print-header" style="display:none;"> <p class="nist-print-header__url">https://www.nist.gov/services-resources/standards-and-measurements</p> <img class="nist-print-header__logo" width="289" height="38" src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/logo/nist_logo_sidestack.svg" alt="National Institute of Standards and Technology"/> </div> <div class="usa-overlay"></div> <header class="usa-header nist-header--www nist-header--minimal" role="banner"> <div class="usa-navbar"> <div class="usa-logo flex-fill"> <a href="/web/20240226172038/https://www.nist.gov/" title="National Institute of Standards and Technology" aria-label="Home"> <img src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/logo/logo.svg" alt="National Institute of Standards and Technology" width="300px" height="80px"/> </a> </div> <div class="usa-header__right grid-row flex-auto"> <div class="grid-col-fill nist-header__search-group"> <form class="usa-search usa-search--small" accept-charset="UTF-8" action="/web/20240226172038/https://www.nist.gov/search" id="search_form" method="get"> <div role="search"> <label class="usa-sr-only" for="search-form">Search NIST</label> <input class="usa-input" id="search-form" type="search" name="s" placeholder="Search NIST" required="" maxlength="128"> <button class="usa-button" type="submit"><img src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/usa-icons-bg/search--white.svg" class="usa-search__submit-icon" alt="Search"></button> </div> </form> </div> <div class="grid-col-auto padding-left-1"> <button class="usa-menu-btn">Menu</button> </div> </div> </div> <nav aria-label="Primary navigation" class="usa-nav"> <div class="usa-nav__inner"> <button class="usa-nav__close">Close</button> <ul class="usa-nav__primary usa-accordion"> <li class="usa-nav__primary-item"> <button class="usa-accordion__button usa-nav__link" aria-expanded="false" aria-controls="primary_menu-1"><span>Topics</span></button> <div id="primary_menu-1" class="usa-nav__submenu usa-megamenu"> <div class="grid-row"> <div class="tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/topics" class="usa-nav__link">All Topics</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/advanced-communications" class="usa-nav__link">Advanced communications</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/artificial-intelligence" class="usa-nav__link">Artificial intelligence</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/bioscience" class="usa-nav__link">Bioscience</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/buildings-construction" class="usa-nav__link">Buildings and construction</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/chemistry" class="usa-nav__link">Chemistry</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/climate" class="usa-nav__link">Climate</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/cybersecurity" class="usa-nav__link">Cybersecurity</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/electronics" class="usa-nav__link">Electronics</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/energy" class="usa-nav__link">Energy</a> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/environment" class="usa-nav__link">Environment</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/fire" class="usa-nav__link">Fire</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/forensic-science" class="usa-nav__link">Forensic science</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/health" class="usa-nav__link">Health</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/information-technology" class="usa-nav__link">Information technology</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/infrastructure" class="usa-nav__link">Infrastructure</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/manufacturing" class="usa-nav__link">Manufacturing</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/materials" class="usa-nav__link">Materials</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/mathematics-statistics" class="usa-nav__link">Mathematics and statistics</a> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/metrology" class="usa-nav__link">Metrology</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/nanotechnology" class="usa-nav__link">Nanotechnology</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/neutron-research" class="usa-nav__link">Neutron research</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/performance-excellence" class="usa-nav__link">Performance excellence</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/physics" class="usa-nav__link">Physics</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/public-safety" class="usa-nav__link">Public safety</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/resilience" class="usa-nav__link">Resilience</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/standards" class="usa-nav__link">Standards</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/transportation" class="usa-nav__link">Transportation</a> </li> </ul> </div> </div> </div> </li> <li class="usa-nav__primary-item"> <a class="usa-nav__link" href="/web/20240226172038/https://www.nist.gov/publications">Publications</a> </li> <li class="usa-nav__primary-item"> <button class="usa-accordion__button usa-nav__link" aria-expanded="false" aria-controls="primary_menu-3"><span>Labs & Major Programs</span></button> <div id="primary_menu-3" class="usa-nav__submenu usa-megamenu"> <div class="grid-row"> <div class="tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/laboratories" class="usa-nav__link">Laboratories</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240226172038/https://www.nist.gov/ctl" class="usa-nav__link">Communications Technology Laboratory</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/el" class="usa-nav__link">Engineering Laboratory</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/itl" class="usa-nav__link">Information Technology Laboratory</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/mml" class="usa-nav__link">Material Measurement Laboratory</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/pml" class="usa-nav__link">Physical Measurement Laboratory</a> </li> </ul> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/user-facilities" class="usa-nav__link">User Facilities</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240226172038/https://www.nist.gov/ncnr" class="usa-nav__link">NIST Center for Neutron Research</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/cnst" class="usa-nav__link">CNST NanoFab</a> </li> </ul> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/labs-major-programs/research-test-beds" class="usa-nav__link">Research Test Beds</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/laboratories/projects-programs" class="usa-nav__link">Research Projects</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/laboratories/tools-instruments" class="usa-nav__link">Tools & Instruments</a> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/major-programs" class="usa-nav__link">Major Programs</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240226172038/https://www.nist.gov/baldrige" class="usa-nav__link">Baldrige Performance Excellence Program</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/chips" class="usa-nav__link">CHIPS for America Initiative</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/mep" class="usa-nav__link">Manufacturing Extension Partnership (MEP)</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/oam" class="usa-nav__link">Office of Advanced Manufacturing</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/spo" class="usa-nav__link">Special Programs Office</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/tpo" class="usa-nav__link">Technology Partnerships Office</a> </li> </ul> </li> </ul> </div> </div> </div> </li> <li class="usa-nav__primary-item"> <button class="usa-accordion__button usa-nav__link usa-current" aria-expanded="false" aria-controls="primary_menu-4"><span>Services & Resources</span></button> <div id="primary_menu-4" class="usa-nav__submenu usa-megamenu"> <div class="grid-row"> <div class="tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/services-resources/standards-and-measurements" class="usa-nav__link usa-current">Standards and Measurements</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240226172038/https://www.nist.gov/calibrations" class="usa-nav__link">Calibration Services</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/nvlap" class="usa-nav__link">Laboratory Accreditation (NVLAP)</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/nist-quality-system" class="usa-nav__link">Quality System</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/srm" class="usa-nav__link">Standard Reference Materials (SRMs)</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/standardsgov" class="usa-nav__link">Standards.gov</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/pml/time-and-frequency-division/time-services" class="usa-nav__link">Time Services</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/pml/owm" class="usa-nav__link">Office of Weights and Measures</a> </li> </ul> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/services-resources/software" class="usa-nav__link">Software</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/data" class="usa-nav__link">Data</a> <ul class="usa-nav__submenu-list"> <li> <a href="https://web.archive.org/web/20240226172038/https://webbook.nist.gov/chemistry/" class="usa-nav__link">Chemistry WebBook</a> </li> <li> <a href="https://web.archive.org/web/20240226172038/https://nvd.nist.gov/" class="usa-nav__link">National Vulnerability Database</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/pml/productsservices/physical-reference-data" class="usa-nav__link">Physical Reference Data</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/srd" class="usa-nav__link">Standard Reference Data (SRD)</a> </li> </ul> </li> <li class="usa-nav__submenu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/shop" class="usa-nav__link">Storefront</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/tpo" class="usa-nav__link">License & Patents</a> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="https://web.archive.org/web/20240226172038/https://csrc.nist.gov/" class="usa-nav__link">Computer Security Resource Center (CSRC)</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/nist-research-library" class="usa-nav__link">NIST Research Library</a> </li> </ul> </div> </div> </div> </li> <li class="usa-nav__primary-item"> <button class="usa-accordion__button usa-nav__link" aria-expanded="false" aria-controls="primary_menu-5"><span>News & Events</span></button> <div id="primary_menu-5" class="usa-nav__submenu usa-megamenu"> <div class="grid-row"> <div class="tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/news-events/news" class="usa-nav__link">News</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/news-events/events" class="usa-nav__link">Events</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/blogs" class="usa-nav__link">Blogs</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/feature-stories" class="usa-nav__link">Feature Stories</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/awards" class="usa-nav__link">Awards</a> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/video-gallery" class="usa-nav__link">Video Gallery</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/image-gallery" class="usa-nav__link">Image Gallery</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/pao/media-contacts" class="usa-nav__link">Media Contacts</a> </li> </ul> </div> </div> </div> </li> <li class="usa-nav__primary-item"> <button class="usa-accordion__button usa-nav__link" aria-expanded="false" aria-controls="primary_menu-6"><span>About NIST</span></button> <div id="primary_menu-6" class="usa-nav__submenu usa-megamenu"> <div class="grid-row"> <div class="tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/about-nist" class="usa-nav__link">About Us</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/about-nist/contact-us" class="usa-nav__link">Contact Us</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/about-nist/visit" class="usa-nav__link">Visit</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/careers" class="usa-nav__link">Careers</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/director/nist-organization-structure" class="usa-nav__link">Our Organization</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240226172038/https://www.nist.gov/director" class="usa-nav__link">Office of the Director</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/director/nist-organization-structure/budget-planning" class="usa-nav__link">Budget & Planning</a> </li> </ul> </li> </ul></div><div class="column-break tablet:grid-col-fill"><ul class="usa-nav__submenu-list"> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/about-nist/work-nist" class="usa-nav__link">Work with NIST</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/history" class="usa-nav__link">History</a> <ul class="usa-nav__submenu-list"> <li> <a href="https://web.archive.org/web/20240226172038/http://nistdigitalarchives.contentdm.oclc.org/" class="usa-nav__link">NIST Digital Archives</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/nist-museum" class="usa-nav__link">NIST Museum</a> </li> <li> <a href="/web/20240226172038/https://www.nist.gov/nist-and-nobel" class="usa-nav__link">NIST and the Nobel</a> </li> </ul> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240226172038/https://www.nist.gov/education" class="usa-nav__link">Educational Resources</a> </li> </ul> </div> </div> </div> </li> </ul> </div> </nav> </header> <!-- nist-index-ignore-end --> </div> <div class="grid-container"> <div data-drupal-messages-fallback class="hidden"></div> </div> <div id="block-nist-www-content" class="nist-block"> <section class="nist-page__content usa-section clearfix"> <a id="main-content" tabindex="-1"></a> <div class="grid-container margin-top-4"> <div class="grid-row grid-gap-6"> <aside class="nist-page__region nist-page__region--sidebar-first tablet-lg:grid-col-4 desktop-lg:grid-col-3"> <div> <div class="nist-block nist-block--main-menu"> <nav> <ul class="usa-sidenav usa-accordion "> <li class="usa-sidenav__item usa-sidenav__item--parent"> <a href="/web/20240226172038/https://www.nist.gov/services-resources/standards-and-measurements" class="usa-current" data-drupal-link-system-path="">Standards and Measurements</a> <button class="usa-accordion__button" aria-expanded="true" aria-controls="main-1"><span class="usa-sr-only">Expand or Collapse</span></button> <ul id="main-1" class="usa-sidenav__sublist usa-accordion"> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/calibrations" data-drupal-link-system-path="">Calibration Services</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/nvlap" data-drupal-link-system-path="">Laboratory Accreditation (NVLAP)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/nist-quality-system" data-drupal-link-system-path="">Quality System</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/srm" data-drupal-link-system-path="">Standard Reference Materials (SRMs)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/standardsgov" data-drupal-link-system-path="">Standards.gov</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/pml/time-and-frequency-division/time-services" data-drupal-link-system-path="">Time Services</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/pml/owm" data-drupal-link-system-path="">Office of Weights and Measures</a> </li> </ul> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/services-resources/software" data-drupal-link-system-path="">Software</a> </li> <li class="usa-sidenav__item usa-sidenav__item--parent"> <a href="/web/20240226172038/https://www.nist.gov/data" data-drupal-link-system-path="">Data</a> <button class="usa-accordion__button" aria-expanded="false" aria-controls="main-3"><span class="usa-sr-only">Expand or Collapse</span></button> <ul id="main-3" class="usa-sidenav__sublist usa-accordion"> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20240226172038/https://webbook.nist.gov/chemistry/" data-drupal-link-system-path="">Chemistry WebBook</a> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20240226172038/https://nvd.nist.gov/" data-drupal-link-system-path="">National Vulnerability Database</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/pml/productsservices/physical-reference-data" data-drupal-link-system-path="">Physical Reference Data</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/srd" data-drupal-link-system-path="">Standard Reference Data (SRD)</a> </li> </ul> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/shop" data-drupal-link-system-path="">Storefront</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/tpo" data-drupal-link-system-path="">License & Patents</a> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20240226172038/https://csrc.nist.gov/" data-drupal-link-system-path="">Computer Security Resource Center (CSRC)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20240226172038/https://www.nist.gov/nist-research-library" data-drupal-link-system-path="">NIST Research Library</a> </li> </ul> </nav> </div> </div> </aside> <div class="nist-page__region nist-page__region--content tablet-lg:grid-col-8 desktop-lg:grid-col-9"> <div class="nist-block"> <h1 class="nist-page__title">Standards & Measurements</h1> </div> <div class="nist-block"> <!-- nist-index-ignore-start --> <div data-elastic-exclude class="nist-block nist-social__wrapper"> <h2 class="nist-social__title">Share</h2> <div class="social-media-sharing"> <div class="nist-social__wrapper--share"> <div> <a target="_blank" rel="noopener" href="https://web.archive.org/web/20240226172038/https://www.facebook.com/share.php?u=https://www.nist.gov/services-resources/standards-and-measurements" title="Facebook" class="nist-social nist-social--facebook-gray"> <span>Facebook</span> </a> </div> <div> <a target="_blank" rel="noopener" href="https://web.archive.org/web/20240226172038/https://www.linkedin.com/shareArticle?mini=true&url=https://www.nist.gov/services-resources/standards-and-measurements&source=https://www.nist.gov/services-resources/standards-and-measurements" title="Linkedin" class="nist-social nist-social--linkedin-gray"> <span>Linkedin</span> </a> </div> <div> <a target="_blank" rel="noopener" href="https://web.archive.org/web/20240226172038/https://twitter.com/intent/tweet?url=https://www.nist.gov/services-resources/standards-and-measurements&status=https://www.nist.gov/services-resources/standards-and-measurements" title="Twitter" class="nist-social nist-social--twitter-gray"> <span>Twitter</span> </a> </div> <div> <a href="https://web.archive.org/web/20240226172038/mailto:/?subject=NIST.gov&body=Check out this site https://www.nist.gov/services-resources/standards-and-measurements" title="Email" class="nist-social nist-social--envelope-gray"> <span>Email</span> </a> </div> </div> </div> </div> <!-- nist-index-ignore-end --> </div> <div class="nist-block"> <div class="text-with-summary"> <p>Standards allow technology to work seamlessly and establish trust so that markets can operate smoothly. They:</p> <ul><li>provide a common language to measure and evaluate performance,</li> <li>make interoperability of components made by different companies possible, and</li> <li>protect consumers by ensuring safety, durability, and market equity.</li> </ul><p>NIST’s portfolio of services for measurements, standards, and legal metrology provides solutions that ensure measurement traceability, enable quality assurance, and harmonize documentary standards and regulatory practices. The tools, information, and training provided by NIST, and the contributions and results produced by its staff, lead to advancements in research and technological innovation that foster the drivers of the U.S. economy: invention, improvement, and commercialization.</p> <h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="d731b841-8e78-4fd4-9e23-8c9a41e30b3b" href="/web/20240226172038/https://www.nist.gov/calibrations" title="Calibrations">Calibration Services</a></h2> <p>NIST provides calibration services to disseminate the primary physical measurement standards for the U.S. for commerce, industry, and research. Calibration services allow customers to achieve the highest quality in their measurement systems, and to provide assurance in their results, by communicating the NIST measurement results for carefully selected instruments and artifacts.</p> <h2>Conformity Assessment</h2> <p>Conformity assessment is the demonstration that specified requirements relating to a product, process, system, person or body are fulfilled. Conformity assessment can include: supplier’s declaration of conformity, sampling and testing, inspection, certification, management system assessment and registration, the accreditation of the competence of those activities, and recognition of an accreditation program’s capability. Under the National Technology Transfer and Advancement Act (NTTAA), NIST is assigned responsibility to coordinate federal, state, and local documentary standards and conformity assessment activities.</p> <ul><li><a href="https://web.archive.org/web/20240226172038/https://www.govinfo.gov/content/pkg/FR-2000-08-10/pdf/00-20262.pdf">Guidance on Federal Conformity Assessment Activities</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="299ea1f6-59ca-4645-a8df-cac8964080e2" href="/web/20240226172038/https://www.nist.gov/standardsgov/national-voluntary-conformity-assessment-systems-evaluation-nvcase" title="National Voluntary Conformity Assessment Systems Evaluation (NVCASE)">National Voluntary Conformity Assessment System Evaluation</a> (NVCASE)</li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="e1e059d6-c5af-443d-974c-faa6ec719b6e" href="/web/20240226172038/https://www.nist.gov/nvlap" title="National Voluntary Laboratory Accreditation Program (NVLAP)">National Voluntary Laboratory Accreditation Program</a> (NVLAP)</li> </ul><h2>Documentary Standards</h2> <p>Documentary standards can specify definition of terms; classifications of components; delineation of procedures; specification of dimensions, materials, processes, products, systems, services or practices; test methods and sampling procedures; or descriptions of fit and measurements of size or strength. Under the National Technology Transfer and Advancement Act (NTTAA), NIST is assigned responsibility to coordinate federal, state, and local documentary standards and conformity assessment activities.</p> <ul><li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="92cb2812-889e-4c18-a2a6-b190bfb128bf" href="/web/20240226172038/https://www.nist.gov/standardsgov" title="Standards.gov">Standards.gov</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="9f18c5d5-f23f-4a81-86ae-db4088b6a296" href="/web/20240226172038/https://www.nist.gov/standardsgov/what-we-do/federal-policy-standards" title="Federal Policy on Standards">Federal Use of Standards</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="4576fe38-11ee-4b01-98ff-3cccadef67c1" href="/web/20240226172038/https://www.nist.gov/standardsgov/standards-incorporated-reference" title="Standards Incorporated by Reference">Standards Incorporated by Reference</a> (SIBR)</li> </ul><h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="e1e059d6-c5af-443d-974c-faa6ec719b6e" href="/web/20240226172038/https://www.nist.gov/nvlap" title="National Voluntary Laboratory Accreditation Program (NVLAP)">Laboratory Accreditation</a></h2> <p>The National Voluntary Laboratory Accreditation Program (NVLAP) provides third-party accreditation to testing and calibration laboratories in response to legislative actions or requests from government agencies or private-sector organizations. NVLAP-accredited laboratories are assessed against the management and technical requirements published in the International Standard, ISO/IEC 17025:2017.</p> <ul><li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="4ef060be-9972-458d-a551-b815d02224ff" href="/web/20240226172038/https://www.nist.gov/nvlap/about-nvlap" title="About NVLAP">About NVLAP</a></li> <li><a href="https://web.archive.org/web/20240226172038/https://www-s.nist.gov/niws/index.cfm?event=directory.search#no-back">Directory of NVLAP-Accredited Laboratories</a></li> <li><a href="https://web.archive.org/web/20240226172038/https://www-s.nist.gov/niws/index.cfm?event=productlist.search#no-back">Search for Test Methods & Calibration Parameters</a></li> </ul><h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="8c64bed9-a554-4519-867f-e6943143f039" href="/web/20240226172038/https://www.nist.gov/nist-quality-system" title="NIST Quality System">NIST Quality System for Measurement Services</a></h2> <p>The NIST Quality System underpins the provision of measurement services: Calibrations and Special Tests, Standard Reference Materials, and Standard Reference Data products. The NIST quality system for measurement services is internationally recognized and meets the requirements of the International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement (MRA) for recognition of national measurement standards. As such, the NIST quality system is recognized as conformant to the ISO/IEC 17025, ISO 17034 and ISO 17043 by the Inter-American Metrology System (SIM) Quality System Task Force and the Joint Committee of the Regional Metrology Organizations and the BIPM (JCRB). The BIPM is the International Bureau of Weights and Measures.</p> <ul><li><a class="media-link-ga " data-entity-substitution="canonical" data-entity-type="media" data-entity-uuid="8a3e8e25-5dd6-45a2-915b-afdcbc95d457" data-file-url="/system/files/documents/2019/04/09/nist_qm-i-v11_controlled_and_signed.pdf" href="/web/20240226172038/https://www.nist.gov/document/nistqm-i-v11controlledandsignedpdf" title="nist_qm-i-v11_controlled_and_signed.pdf">NIST Quality Manual</a></li> </ul><h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="addd9cc9-89c5-4d36-9ced-c68e2d22081f" href="/web/20240226172038/https://www.nist.gov/srd" title="Standard Reference Data">Standard Reference Data</a> (SRD)</h2> <p>For more than 50 years, NIST has developed and distributed Standard Reference Data. Search the NIST Data Gateway and view our list of more than 70 NIST websites dedicated to Standard Reference Data.</p> <ul><li><a href="https://web.archive.org/web/20240226172038/https://data.nist.gov/">NIST Data Gateway</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="6a71582f-807c-4a7b-b929-0863843b94fe" href="/web/20240226172038/https://www.nist.gov/srd/srd-catalog" title="SRD Catalog">Free Standard Reference Databases</a></li> </ul><h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="b826c90d-7086-4f91-b38d-9dfcb18880d3" href="/web/20240226172038/https://www.nist.gov/sri/standard-reference-instruments" title="Standard Reference Instruments">Standard Reference Instruments</a> (SRI)</h2> <p>NIST supports accurate and compatible measurements by producing and providing Standard Reference Instruments that transfer to customers the ability to make reference measurements or generate reference responses based on specific NIST reference instrument designs.</p> <h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="5146823c-a457-49d6-923b-bd22e353a548" href="/web/20240226172038/https://www.nist.gov/srm" title="Standard Reference Materials">Standard Reference Materials</a> (SRM)</h2> <p>NIST supports accurate and compatible measurements by certifying and providing more than 1,200 Standard Reference Materials® with well-characterized composition or properties, or both. These materials are used to perform instrument calibrations in units as part of overall quality assurance programs, to verify the accuracy of specific measurements and to support the development of new measurement methods.</p> <ul><li><a href="https://web.archive.org/web/20240226172038/https://www-s.nist.gov/srmors/">Search the SRM Catalog</a></li> </ul><h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="92cb2812-889e-4c18-a2a6-b190bfb128bf" href="/web/20240226172038/https://www.nist.gov/standardsgov" title="Standards.gov">Standards.gov</a></h2> <p>Standards.gov is your pathway to standards solutions. Maintained by the NIST Standards Coordination Office, this website provide tools, programs, services and educational resources about documentary standards and conformity assessment. </p> <ul><li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="cf908f32-2012-4b20-a1c2-0aaba4833bec" href="/web/20240226172038/https://www.nist.gov/standardsgov/usa-tbt-enquiry-point" title="USA TBT Enquiry Point">U.S. WTO TBT Inquiry Point & Notify U.S.</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="9f18c5d5-f23f-4a81-86ae-db4088b6a296" href="/web/20240226172038/https://www.nist.gov/standardsgov/what-we-do/federal-policy-standards" title="Federal Policy on Standards">Federal Policy on Standards</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="4576fe38-11ee-4b01-98ff-3cccadef67c1" href="/web/20240226172038/https://www.nist.gov/standardsgov/standards-incorporated-reference" title="Standards Incorporated by Reference">Standards Incorporated by Reference (SIBR) Database</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="45aab89f-e344-4f15-b125-175c5b59b3ff" href="/web/20240226172038/https://www.nist.gov/standardsgov/standards-information-center" title="Standards Information Center">Standards Information Center</a></li> </ul><h2>Time Services</h2> <p>Whether you need to synchronize your computer’s clock using our online tools or find data about recent leap seconds, NIST Internet Time Services (ITS) has the information you need. NIST operates several stratum-1 network time servers, which means their time is directly linked to UTC(NIST), the official NIST time. ITS also provides information on protocols and authentication such as the DAYTIME, TIME, and NTP protocols.</p> <ul><li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="7f3ea4b1-a4dc-4fb8-ab17-8e78e6a217e4" href="/web/20240226172038/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/internet-time-service-its" title="NIST Internet Time Service (ITS)">NIST Internet Time Services</a> (ITS)</li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="1eaed78f-3e31-44f7-85ba-c18b47383b14" href="/web/20240226172038/https://www.nist.gov/pml/time-and-frequency-division/time-and-frequency-metrology" title="Phase Noise Metrology Group">Time & Frequency Metrology</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="d613428d-8936-4bd0-a944-e9694b5b2204" href="/web/20240226172038/https://www.nist.gov/programs-projects/time-measurement-and-analysis-service-tmas" title="Time Measurement and Analysis Service (TMAS)">Time Calibrations</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="b2d9874a-d7ae-4aae-bf26-749f4095459f" href="/web/20240226172038/https://www.nist.gov/pml/time-and-frequency-division/time-realization/utcnist-time-scale" title="UTC(NIST) Time Scale">Time Scales</a></li> <li><a href="https://web.archive.org/web/20240226172038/http://www.time.gov/">Time.gov</a></li> </ul><h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="ee76c8cc-2bb0-4c24-b9ad-40d30236458d" href="/web/20240226172038/https://www.nist.gov/calibrations/traceability" title="NIST Policy on Metrological Traceability">Traceability</a></h2> <p>NIST has developed an organizational policy on metrological traceability and a set of related supplementary materials, which includes answers to questions frequently asked by customers of NIST measurement services. NIST is responsible for developing, maintaining and disseminating national standards — realizations of the SI — for the basic measurement quantities, and for many derived measurement quantities. NIST is also responsible for assessing the measurement uncertainties associated with the values assigned to these measurement standards.</p> <h2><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="2b809e98-67a7-4a1f-8dca-4d7f42e6e539" href="/web/20240226172038/https://www.nist.gov/pml/owm" title="Office of Weights and Measures">Office of Weights and Measures</a></h2> <p>Our mission is to improve the accuracy of measurements, enhance consumer protection, foster fair competition, and facilitate economic growth and trade through technical activities that promote uniformity in national and international legal metrology laws, regulations, standards, test procedures, and enforcement.</p> <ul><li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="f28337b2-3c56-4bce-990f-ba4e856170c5" href="/web/20240226172038/https://www.nist.gov/pml/owm/owm-training-and-events" title="OWM Training and Events">Training and Events Calendar</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="add127e0-ebf3-44c3-acfb-861a259ee2f5" href="/web/20240226172038/https://www.nist.gov/pml/owm/owm-products-and-services/publications-and-documentary-standards" title="OWM Publications and Documentary Standards">Publications</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="71a74af0-9396-4df2-ae65-dd2f62bfa04c" href="/web/20240226172038/https://www.nist.gov/pml/owm/external-resources-weights-and-measures" title="External Resources for Weights and Measures">Resources</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="3c32ba8c-656e-4b59-824c-0fade928dccc" href="/web/20240226172038/https://www.nist.gov/pml/owm/programsgroups" title="OWM Program Areas/Groups">Programs</a></li> </ul> </div> </div> </div> </div> </div> <div class="grid-container"> <div class="nist-page__region nist-page__region--content-bottom"> <div class="nist-block"> <div class="text-italic font-sans-2xs"> Created June 22, 2015, Updated January 18, 2022 </div> </div> </div> </div> </section> </div> <div data-elastic-exclude> <!-- nist-index-ignore-start --> <footer class="nist-footer padding-bottom-4"> <div class="grid-container nist-footer__info"> <div class="grid-row"> <div class="tablet:grid-col-6"> <div class="nist-footer__logo"> <a href="/web/20240226172038/https://www.nist.gov/" title="National Institute of Standards and Technology" rel="home"> <img class="nist-footer__logo-img" src="/web/20240226172038im_/https://www.nist.gov/libraries/nist-component-library/dist/img/logo/NIST-Logo-Brand-White.svg" alt="National Institute of Standards and Technology logo" width="300px" height="42px"/> </a> </div> <div class="nist-footer__contact"> <h3 class="nist-footer__contact-heading">HEADQUARTERS</h3> <address> 100 Bureau Drive<br> Gaithersburg, MD 20899<br> <a href="https://web.archive.org/web/20240226172038/tel:301-975-2000">301-975-2000</a> </address> <p> <a href="https://web.archive.org/web/20240226172038/mailto:do-webmaster@nist.gov">Webmaster</a> | <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/about-nist/contact-us">Contact Us</a> | <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/visit">Our Other Offices</a> </p> </div> </div> <div class="tablet:grid-col-6"> <div class="nist-footer__social-links"> <a class="nist-social nist-social--twitter-white" href="https://web.archive.org/web/20240226172038/https://twitter.com/NIST"> <span>Twitter</span> </a> <a class="nist-social nist-social--facebook-white" href="https://web.archive.org/web/20240226172038/https://www.facebook.com/NIST"> <span>Facebook</span> </a> <a class="nist-social nist-social--linkedin-white" href="https://web.archive.org/web/20240226172038/https://www.linkedin.com/company/nist"> <span>LinkedIn</span> </a> <a class="nist-social nist-social--instagram-white" href="https://web.archive.org/web/20240226172038/https://www.instagram.com/nist/"> <span>Instagram</span> </a> <a class="nist-social nist-social--youtube-white" href="https://web.archive.org/web/20240226172038/https://www.youtube.com/NIST"> <span>YouTube</span> </a> <a class="nist-social nist-social--giphy-white" href="https://web.archive.org/web/20240226172038/https://giphy.com/nist"> <span>Giphy</span> </a> <a class="nist-social nist-social--rss-white" href="https://web.archive.org/web/20240226172038/https://www.nist.gov/news-events/nist-rss-feeds"> <span>RSS Feed</span> </a> <a class="nist-social nist-social--envelope-white" href="https://web.archive.org/web/20240226172038/https://public.govdelivery.com/accounts/USNIST/subscriber/new"> <span>Mailing List</span> </a> </div> <div class="nist-footer__feedback"> How are we doing? <a class="usa-button" rel="nofollow" href="/web/20240226172038/https://www.nist.gov/form/nist-gov-feedback?destination=/services-resources/standards-and-measurements" title="Provide feedback">Feedback</a> </div> </div> </div> </div> <div class="grid-container"> <div class="nist-footer__nav" role="navigation"> <ul> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/privacy-policy">Site Privacy</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/oism/accessibility">Accessibility</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/privacy">Privacy Program</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/oism/copyrights">Copyrights</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.commerce.gov/vulnerability-disclosure-policy">Vulnerability Disclosure</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/no-fear-act-policy">No Fear Act Policy</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/office-director/freedom-information-act">FOIA</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/environmental-policy-statement">Environmental Policy</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/summary-report-scientific-integrity">Scientific Integrity</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.nist.gov/nist-information-quality-standards">Information Quality Standards</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://www.commerce.gov/">Commerce.gov</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/http://www.science.gov/">Science.gov</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/http://www.usa.gov/">USA.gov</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240226172038/https://vote.gov/">Vote.gov</a> </li> </ul> </div> </div> </footer> <!-- nist-index-ignore-end --> </div> </div> <script type="application/json" data-drupal-selector="drupal-settings-json">{"path":{"baseUrl":"\/","scriptPath":null,"pathPrefix":"","currentPath":"node\/386181","currentPathIsAdmin":false,"isFront":false,"currentLanguage":"en"},"pluralDelimiter":"\u0003","suppressDeprecationErrors":true,"back_to_top":{"back_to_top_button_trigger":100,"back_to_top_prevent_on_mobile":false,"back_to_top_prevent_in_admin":true,"back_to_top_button_type":"image","back_to_top_button_text":"Back to top"},"google_analytics":{"account":"G-HEQ0YF2VYL","trackOutbound":true,"trackMailto":true,"trackTel":true,"trackDownload":true,"trackDownloadExtensions":"7z|aac|arc|arj|asf|asx|avi|bin|bsh|c|csv|doc(x|m)?|dot(x|m)?|dw(fx|g|gd)|dxf|eps|epub|exe|f(90)|flv|gif|gz|gzip|hqx|jar|jpe?g|js|m1v|mp(2|3|4|e?g)|mobi|mov(ie)?|msi|msp|pdf|phps|pl|png|ppt(x|m)?|pot(x|m)?|pps(x|m)?|ppam|sld(x|m)?|thmx|qtm?|ra(m|r)?|rfa|rtf|rvt|sch|sea|sit|swf|tar|tgz|tif|txt|txz|wav|wma|wmv|wpd|wrl|xls(x|m|b)?|xlt(x|m)|xlam|xml|xsd|z|zip"},"nist_search":{"clickTracking":"search-report-click","isDebug":false,"clickTrackEnabled":true,"message":"NIST Search in debug mode. Check the browsers network inspector for Click Track reporting results..."},"data":{"extlink":{"extTarget":false,"extTargetNoOverride":false,"extNofollow":false,"extNoreferrer":false,"extFollowNoOverride":false,"extClass":"ext","extLabel":"(link is external)","extImgClass":false,"extSubdomains":true,"extExclude":"\\.gov\\\/|\\.mil\\\/|\\manufacturingusa\\.com\\\/","extInclude":"","extCssExclude":".ck-editor, .nist-social, .nist-video-thumbnail__lightbox-trigger, a.nist-icon--mail-blue","extCssExplicit":"","extAlert":true,"extAlertText":"Thank you for visiting NIST. We hope your visit was informative. We have provided a link to this site because it has information that may be of interest to our users. NIST does not necessarily endorse the views expressed or the facts presented on this site. Further, NIST does not endorse any commercial products that may be advertised or available on this site. Click OK to be directed to your link.","mailtoClass":"0","mailtoLabel":"(link sends email)","extUseFontAwesome":false,"extIconPlacement":"after","extFaLinkClasses":"fa fa-external-link","extFaMailtoClasses":"fa fa-envelope-o","whitelistedDomains":[]}},"user":{"uid":0,"permissionsHash":"2f77e4dcfce20728ac491170886da836c10b580f9bdfeb9c9e729fe4958834d5"}}</script> <script src="/web/20240226172038js_/https://www.nist.gov/sites/default/files/js/js_L4s-xoxkQ67XMK98eQiz0h1j1ibNkR1AmjhYszY77y0.js?scope=footer&delta=0&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"></script> <script src="https://web.archive.org/web/20240226172038js_/https://siteimproveanalytics.com/js/siteanalyze_6017546.js" async></script> <script src="/web/20240226172038js_/https://www.nist.gov/sites/default/files/js/js_3eRXHrPpksrnWG1E8OJzoaq-9enhLNMMVm0GPoHbKRs.js?scope=footer&delta=2&language=en&theme=nist_www&include=eJx1T9EOAiEM-yGUTyIDJs4b7MJQ9O-FU-PFxGQPa9e1m4ewuCajVuu_vbuo8X9GFKSYJJIYHRTgR6Og9pcwhbS5Ew0uSi8sEF2rw4ZKsgleY6WGlNcqN7S_xDxh49oZM45kYQ_VZYk2koIfxkxlMfrQhnlcqLjpbWLxwPv-8LayZ4SI9QNd732v3uEpwXubATbW6wp8fEOjEgjYZYwEM5XCdzlTqDJ_eAJxaYdI"></script> <script type="text/javascript">window.NREUM||(NREUM={});NREUM.info={"beacon":"bam.nr-data.net","licenseKey":"37b7ccb661","applicationID":"1089704227","transactionName":"YFxUN0sADEdYVkBaClkWdwBNCA1aFkVVVABoWlcAUQQ=","queueTime":4,"applicationTime":53,"atts":"TBtXQQMaH0k=","errorBeacon":"bam.nr-data.net","agent":""}</script></body> </html> <!-- FILE ARCHIVED ON 17:20:38 Feb 26, 2024 AND RETRIEVED FROM THE INTERNET ARCHIVE ON 19:57:14 Dec 02, 2024. JAVASCRIPT APPENDED BY WAYBACK MACHINE, COPYRIGHT INTERNET ARCHIVE. ALL OTHER CONTENT MAY ALSO BE PROTECTED BY COPYRIGHT (17 U.S.C. SECTION 108(a)(3)). --> <!-- playback timings (ms): captures_list: 0.691 exclusion.robots: 0.038 exclusion.robots.policy: 0.022 esindex: 0.017 cdx.remote: 110.166 LoadShardBlock: 257.252 (3) PetaboxLoader3.datanode: 154.007 (4) PetaboxLoader3.resolve: 195.522 (2) load_resource: 259.801 -->