What is a Standard Reference Material or SRM?

<!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/video/what-standard-reference-material-or-srm","20240117020314","https://web.archive.org/","web","/_static/", "1705456994"); </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" />  <meta charset="utf-8"/><script type="text/javascript">(window.NREUM||(NREUM={})).init={ajax:{deny_list:["gov-bam.nr-data.net"]}};(window.NREUM||(NREUM={})).loader_config={licenseKey:"37b7ccb661",applicationID:"1089704227"};;/*! For license information please see nr-loader-rum-1.250.0.min.js.LICENSE.txt */ (()=>{var e,t,r={234:(e,t,r)=>{"use strict";r.d(t,{P_:()=>v,Mt:()=>b,C5:()=>s,DL:()=>A,OP:()=>S,lF:()=>T,Yu:()=>x,Dg:()=>m,CX:()=>c,GE:()=>_,sU:()=>R});var n=r(8632),i=r(9567);const a={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},o={};function s(e){if(!e)throw new Error("All info objects require an agent identifier!");if(!o[e])throw new Error("Info for ".concat(e," was never set"));return o[e]}function c(e,t){if(!e)throw new Error("All info objects require an agent identifier!");o[e]=(0,i.D)(t,a);const r=(0,n.ek)(e);r&&(r.info=o[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:50,error_sampling_rate:50,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},w={};function A(e){if(!e)throw new Error("All loader-config objects require an agent identifier!");if(!w[e])throw new Error("LoaderConfig for ".concat(e," was never set"));return w[e]}function _(e,t){if(!e)throw new Error("All loader-config objects require an agent identifier!");w[e]=(0,i.D)(t,y);const r=(0,n.ek)(e);r&&(r.loader_config=w[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)),a=0===Object.keys(r).length?e:r;for(let o in a)if(void 0!==e[o])try{Array.isArray(e[o])&&Array.isArray(t[o])?r[o]=Array.from(new Set([...e[o],...t[o]])):"object"==typeof e[o]&&"object"==typeof t[o]?r[o]=i(e[o],t[o]):r[o]=e[o]}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:()=>a,q4:()=>n});const n="1.250.0",i="PROD",a="CDN"},385:(e,t,r)=>{"use strict";r.d(t,{Nk:()=>d,Tt:()=>s,_A:()=>a,cv:()=>l,iS:()=>o,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),a=n?window:"undefined"!=typeof WorkerGlobalScope&&("undefined"!=typeof self&&self instanceof WorkerGlobalScope&&self||"undefined"!=typeof globalThis&&globalThis instanceof WorkerGlobalScope&&globalThis),o=(a?.document?.readyState,Boolean("hidden"===a?.document?.visibilityState)),s=(a?.location,/iPad|iPhone|iPod/.test(a.navigator?.userAgent)),c=s&&"undefined"==typeof SharedWorker,u=((()=>{const e=a.navigator?.userAgent?.match(/Firefox[/\s](\d+\.\d+)/);Array.isArray(e)&&e.length>=2&&e[1]})(),Boolean(n&&window.document.documentMode)),d=!!a.navigator?.sendBeacon,l=Math.floor(a?.performance?.timeOrigin||a?.performance?.timing?.navigationStart||Date.now())},1117:(e,t,r)=>{"use strict";r.d(t,{w:()=>a});var n=r(50);const i={agentIdentifier:"",ee:void 0};class a{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),a=r(4322),o=r(3325);const s={};function c(e,t){const r={staged:!1,priority:o.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";if(u(e),!e||!s[e].get(t))return o(t);s[e].get(t).staged=!0;const r=[...s[e]];function o(t){const r=e?n.ee.get(e):n.ee,o=a.X.handlers;if(r.backlog&&o){var s=r.backlog[t],c=o[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 o[t],r.backlog[t]=null,r.emit("drain-"+t,[])}}r.every((e=>{let[t,r]=e;return r.staged}))&&(r.sort(((e,t)=>e[1].priority-t[1].priority)),r.forEach((t=>{let[r]=t;s[e].delete(r),o(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],a=e[3],o=e[2];i.apply(a,o)}}))}},8325:(e,t,r)=>{"use strict";r.d(t,{A:()=>c,ee:()=>u});var n=r(8632),i=r(2210),a=r(234);class o{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,a.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,a){!1!==a&&(a=!0);if(u.aborted&&!i)return;t&&a&&t.emit(e,r,n);for(var o=p(n),c=v(e),d=c.length,l=0;l<d;l++)c[l].apply(o,r);var f=b()[s[e]];f&&f.push([g,e,r,o]);return o},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 o?e:e?(0,i.X)(e,c,(()=>new o(c))):new o(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,u.backlog={}}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,a){a?(a.buffer([e],i),a.emit(e,t,r)):(n.buffer([e],i),n.emit(e,t,r))}},4322:(e,t,r)=>{"use strict";r.d(t,{X:()=>a});var n=r(5546);a.on=o;var i=a.handlers={};function a(e,t,r,a){o(a||n.E,i,e,t,r)}function o(e,t,r,i,a){a||(a="feature"),e||(e=n.E);var o=t[a]=t[a]||{};(o[r]=o[r]||[]).push([e,i])}},3239:(e,t,r)=>{"use strict";r.d(t,{bP:()=>s,iz:()=>c,m$:()=>o});var n=r(385);let i=!1,a=!1;try{const e={get passive(){return i=!0,!1},get signal(){return a=!0,!1}};n._A.addEventListener("test",null,e),n._A.removeEventListener("test",null,e)}catch(e){}function o(e,t){return i||a?{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,o(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,o(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:()=>o,ky:()=>s});var n=r(385);const i="xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";function a(e,t){return e?15&e[t]:16*Math.random()|0}function o(){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?a(t,r++).toString(16):"y"===e?(3&a()|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 o=[];for(var s=0;s<e;s++)o.push(a(r,i++).toString(16));return o.join("")}},7056:(e,t,r)=>{"use strict";r.d(t,{Bq:()=>n,Hb:()=>a,IK:()=>c,oD:()=>i,uT:()=>s,wO:()=>o});const n="NRBA",i=144e5,a=18e5,o={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),a=r(3325),o=r(385);const s="newrelic";const c={stn:[a.D.sessionTrace],err:[a.D.jserrors,a.D.metrics],ins:[a.D.pageAction],spa:[a.D.spa],sr:[a.D.sessionReplay,a.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{o._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:()=>a});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 a(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:()=>o,b2:()=>a});var n=r(3239);function i(){return"undefined"==typeof document||"complete"===document.readyState}function a(e,t){if(i())return e();(0,n.bP)("load",e,t)}function o(e){if(i())return e();(0,n.iz)("DOMContentLoaded",e)}},8632:(e,t,r)=>{"use strict";r.d(t,{EZ:()=>d,ce:()=>a,ek:()=>u,fP:()=>o,gG:()=>l,h5:()=>c,mF:()=>s});var n=r(7894),i=r(385);const a={beacon:"bam.nr-data.net",errorBeacon:"bam.nr-data.net"};function o(){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=o();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=o();r.initializedAgents??={},t.initializedAt={ms:(0,n.z)(),date:new Date},r.initializedAgents[e]=t}function u(e){let t=o();return t.initializedAgents?.[e]}function d(e,t){o()[e]=t}function l(){return function(){let e=o();const t=e.info||{};e.info={beacon:a.beacon,errorBeacon:a.errorBeacon,...t}}(),function(){let e=o();const t=e.init||{};e.init={...t}}(),s(),function(){let e=o();const t=e.loader_config||{};e.loader_config={...t}}(),o()}},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:()=>a,mY:()=>i,t9:()=>n,vz:()=>s,xS:()=>o});const n=r(3325).D.metrics,i="sm",a="cm",o="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),a=r(5546),o=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 a=[];return Object.values(e.initializedAgents).forEach((e=>{e.exposed&&e.api[t]&&a.push(e.api[t](...n))})),a.length>1?a:a[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:w,info:A,loader_config:_,runtime:x={loaderType:b},exposed:E=!0}=t;const D=(0,g.gG)();A||(w=D.init,A=D.info,_=D.loader_config),(0,i.Dg)(e.agentIdentifier,w||{}),(0,i.GE)(e.agentIdentifier,_||{}),A.jsAttributes??={},d.v6&&(A.jsAttributes.isWorker=!0),(0,i.CX)(e.agentIdentifier,A);const k=(0,i.P_)(e.agentIdentifier),j=[A.beacon,A.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=o.ee.get(e),h=p.get("tracer"),v="api-",m=v+"ixn-";function b(t,r,n,a){const o=(0,i.C5)(e);return null===r?delete o.jsAttributes[t]:(0,i.CX)(e,{...o,jsAttributes:{...o.jsAttributes,[t]:r}}),A(v,n,!0,a||null===r?"session":void 0)(t,r)}function y(){}["setErrorHandler","finished","addToTrace","addRelease"].forEach((e=>{g[e]=A(v,e,!0,"api")})),g.addPageAction=A(v,"addPageAction",!0,n.D.pageAction),g.setCurrentRouteName=A(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/20240117020314/http://custom.transaction")+t,A(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,a.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,a.p)(f.xS,["API/recordReplay/called"],void 0,n.D.metrics,p),(0,a.p)("recordReplay",[],void 0,n.D.sessionReplay,p)},g.pauseReplay=function(){(0,a.p)(f.xS,["API/pauseReplay/called"],void 0,n.D.metrics,p),(0,a.p)("pauseReplay",[],void 0,n.D.sessionReplay,p)},g.interaction=function(){return(new y).get()};var w=y.prototype={createTracer:function(e,t){var r={},i=this,o="function"==typeof t;return(0,a.p)(f.xS,["API/createTracer/called"],void 0,n.D.metrics,p),(0,a.p)(m+"tracer",[(0,s.z)(),e,r],i,n.D.spa,p),function(){if(h.emit((o?"":"no-")+"fn-start",[(0,s.z)(),i,o],r),o)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 A(e,t,r,i){return function(){return(0,a.p)(f.xS,["API/"+t+"/called"],void 0,n.D.metrics,p),i&&(0,a.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...")))}return["actionText","setName","setAttribute","save","ignore","onEnd","getContext","end","get"].forEach((e=>{w[e]=A(m,e,void 0,n.D.spa)})),g.noticeError=function(e,t){"string"==typeof e&&(e=new Error(e)),(0,a.p)(f.xS,["API/noticeError/called"],void 0,n.D.metrics,p),(0,a.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 a=n[e]={exports:{}};return r[e](a,a.exports,i),a.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-1.250.0.min.js",i.o=(e,t)=>Object.prototype.hasOwnProperty.call(e,t),e={},t="NRBA-1.250.0.PROD:",i.l=(r,n,a,o)=>{if(e[r])e[r].push(n);else{var s,c;if(void 0!==a)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+a){s=l;break}}if(!s){c=!0;var f={75:"sha512-2/f4ks7UUkz/V5qC88wpBuGtLglDVUbydMJpZeUMyA/1ChnpO/Q00ZY/7dABphVkZ8zpnV6zFxxikFwJCMiQRg=="};(s=document.createElement("script")).charset="utf-8",s.timeout=120,i.nc&&s.setAttribute("nonce",i.nc),s.setAttribute("data-webpack",t+a),s.src=r,0!==s.src.indexOf(window.location.origin+"/")&&(s.crossOrigin="anonymous"),f[o]&&(s.integrity=f[o])}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/20240117020314/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 a=new Promise(((r,i)=>n=e[t]=[r,i]));r.push(n[2]=a);var o=i.p+i.u(t),s=new Error;i.l(o,(r=>{if(i.o(e,t)&&(0!==(n=e[t])&&(e[t]=void 0),n)){var a=r&&("load"===r.type?"missing":r.type),o=r&&r.target&&r.target.src;s.message="Loading chunk "+t+" failed.\n("+a+": "+o+")",s.name="ChunkLoadError",s.type=a,s.request=o,n[1](s)}}),"chunk-"+t,t)}};var t=(t,r)=>{var n,a,[o,s,c]=r,u=0;if(o.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<o.length;u++)a=o[u],i.o(e,a)&&e[a]&&e[a][0](),e[a]=0},r=self["webpackChunk:NRBA-1.250.0.PROD"]=self["webpackChunk:NRBA-1.250.0.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(e){return"Call to agent api ".concat(e," failed. The agent is not currently initialized.")}addPageAction(t,r){(0,e.Z)(this.#e("addPageAction"))}setPageViewName(t,r){(0,e.Z)(this.#e("setPageViewName"))}setCustomAttribute(t,r,n){(0,e.Z)(this.#e("setCustomAttribute"))}noticeError(t,r){(0,e.Z)(this.#e("noticeError"))}setUserId(t){(0,e.Z)(this.#e("setUserId"))}setApplicationVersion(t){(0,e.Z)(this.#e("setApplicationVersion"))}setErrorHandler(t){(0,e.Z)(this.#e("setErrorHandler"))}finished(t){(0,e.Z)(this.#e("finished"))}addRelease(t,r){(0,e.Z)(this.#e("addRelease"))}start(t){(0,e.Z)(this.#e("start"))}recordReplay(){(0,e.Z)(this.#e("recordReplay"))}pauseReplay(){(0,e.Z)(this.#e("pauseReplay"))}}var r=i(3325),n=i(234);const a=Object.values(r.D);function o(e){const t={};return a.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 a;this.onAggregateImported=new Promise((e=>{a=e}));const o=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 a(!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),a(!0)}catch(t){(0,e.Z)("Downloading and initializing ".concat(this.featureName," failed..."),t),this.abortHandler?.(),(0,c.L)(this.agentIdentifier,this.featureName),a(!1)}};l.il?(0,d.b2)((()=>o()),!0):o()}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 a=this.getBucket(e,t,r,i);return a.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,a.metrics),a}merge(e,t,r,n,i){var a=this.getBucket(e,t,n,i);if(a.metrics){var o=a.metrics;o.count+=r.count,(0,v.D)(r,(function(e,t){if("count"!==e){var n=o[e],i=r[e];i&&!i.c?o[e]=b(i.t,n):o[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,o[e])}}))}else a.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]]=w(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 w(e){return"object"!=typeof e?[]:(0,v.D)(e,A)}function A(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=o(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}}addToTrace(t){(0,e.Z)("Call to agent api addToTrace failed. The session trace feature is not currently initialized.")}setCurrentRouteName(t){(0,e.Z)("Call to agent api setCurrentRouteName failed. The spa feature is not currently initialized.")}interaction(){(0,e.Z)("Call to agent api interaction failed. The spa feature is not currently initialized.")}}({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/20240117020314js_/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});</script> <meta name="description" content="How do you know if the numbers in your lab results or your food's nutritional labels are correct? Labs and manufacturers use Standard Reference Materials or SRMs to make sure that the machines measuring these numbers are accurate. Learn what SRMs are in this animated explainer. For more information"/> <meta name="keywords" content="standard reference material,srm,nist,accuracy,measurement,trust,concrete srm,peanut butter srm,srms,quality,food,biopharmaceutical,industry,buildings,labs,material,cholesterol,things,blood,safety,scenes,technologies,industries,box,bottle"/> <link rel="canonical" href="https://web.archive.org/web/20240117020314/https://www.nist.gov/video/what-standard-reference-material-or-srm"/> <link rel="shortlink" href="https://web.archive.org/web/20240117020314/https://www.nist.gov/media/658051"/> <meta name="citation_title" content="What is a Standard Reference Material or SRM? | NIST"/> <meta property="og:site_name" content="NIST"/> <meta property="og:type" content="video.other"/> <meta property="og:url" content="https://web.archive.org/web/20240117020314/https://www.nist.gov/video/what-standard-reference-material-or-srm"/> <meta property="og:title" content="What is a Standard Reference Material or SRM?"/> <meta property="og:description" content="How do you know if the numbers in your lab results or your food's nutritional labels are correct? Labs and manufacturers use Standard Reference Materials or SRMs to make sure that the machines measuring these numbers are accurate. Learn what SRMs are in this animated explainer. For more information"/> <meta property="og:image" content="https://web.archive.org/web/20240117020314im_/https://cdnsecakmi.kaltura.com/p/684682/sp/68468200/thumbnail/entry_id/1_q0ew7l8z/version/100011/width/480"/> <meta property="og:video" content="https://web.archive.org/web/20240117020314/https://www.kaltura.com/p/684682/sp/68468200/embedIframeJs/uiconf_id/31013851/partner_id/684682?iframeembed=true&entry_id=1_q0ew7l8z"/> <meta property="og:video:secure_url" content="https://web.archive.org/web/20240117020314/https://www.kaltura.com/p/684682/sp/68468200/embedIframeJs/uiconf_id/31013851/partner_id/684682?iframeembed=true&entry_id=1_q0ew7l8z"/> <meta property="og:video:type" content="video.other"/> <meta name="dcterms.title" content="What is a Standard Reference Material or SRM?"/> <meta name="dcterms.description" content="How do you know if the numbers in your lab results or your food's nutritional labels are correct? Labs and manufacturers use Standard Reference Materials or SRMs to make sure that the machines measuring these numbers are accurate. Learn what SRMs are in this animated explainer. For more information"/> <meta name="dcterms.type" content="video"/> <meta name="dcterms.format" content="text/html"/> <meta name="dcterms.identifier" content="https://www.nist.gov/video/what-standard-reference-material-or-srm"/> <meta name="dcterms.source" content="NIST"/> <meta name="twitter:card" content="summary_large_image"/> <meta name="twitter:description" content="How do you know if the numbers in your lab results or your food's nutritional labels are correct? Labs and manufacturers use Standard Reference Materials or SRMs to make sure that the machines measuring these numbers are accurate. Learn what SRMs are in this animated explainer. For more information"/> <meta name="twitter:site" content="NIST"/> <meta name="twitter:title" content="What is a Standard Reference Material or SRM?"/> <meta name="twitter:image" content="https://web.archive.org/web/20240117020314im_/https://cdnsecakmi.kaltura.com/p/684682/sp/68468200/thumbnail/entry_id/1_q0ew7l8z/version/100011/width/480"/> <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"/> <script type="application/ld+json">{ "@context": "https://web.archive.org/web/20240117020314/https://schema.org", "@graph": [ { "@type": "Article", "headline": "What is a Standard Reference Material or SRM? | NIST" } ] }</script> <meta name="nist_search_bundle" class="elastic" content="remote_video"/> <link rel="icon" href="/web/20240117020314im_/https://www.nist.gov/themes/custom/nist_www/favicon.ico" type="image/vnd.microsoft.icon"/> <title>What is a Standard Reference Material or SRM? | NIST</title> <link rel="stylesheet" media="all" href="/web/20240117020314cs_/https://www.nist.gov/sites/default/files/css/css_bqUVis4VEyEFYkB5Zdf6rCAKqdz8p8MARCkEtBk4xrQ.css?delta=0&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"/> <link rel="stylesheet" media="all" href="/web/20240117020314cs_/https://www.nist.gov/sites/default/files/css/css_6prwlieMvitJqVLptJ59w_NxX2prM0abXhYVoH12prk.css?delta=1&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"/> <link rel="stylesheet" media="print" href="/web/20240117020314cs_/https://www.nist.gov/sites/default/files/css/css_6MuKXqcH69mMwmOSjiD2G_c6UXIqUTZ1TRnur95k7Qk.css?delta=2&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"/> <link rel="stylesheet" media="all" href="/web/20240117020314cs_/https://www.nist.gov/sites/default/files/css/css_a_aPvBNLK21ntDbBDMqv_xe37eeWY0ck2ghJ66R_-pI.css?delta=3&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"/> <script src="/web/20240117020314js_/https://www.nist.gov/sites/default/files/js/js_3ssAdmvsW-btol8ydZT2eloQN8l11yuGacOobfI1-_0.js?scope=header&delta=0&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"></script> </head> <body> <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>  <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/20240117020314im_/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鈥檚 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鈥檚 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/20240117020314im_/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/20240117020314im_/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鈥檝e safely connected to the .gov website. Share sensitive information only on official, secure websites. </p> </div> </div> </div> </div> </div> </section>  <div data-elastic-exclude>  <div class="nist-print-header" style="display:none;"> <p class="nist-print-header__url">https://www.nist.gov/video/what-standard-reference-material-or-srm</p> <img class="nist-print-header__logo" width="289" height="38" src="/web/20240117020314im_/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/20240117020314/https://www.nist.gov/" title="National Institute of Standards and Technology" aria-label="Home"> <img src="/web/20240117020314im_/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/20240117020314/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/20240117020314im_/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/20240117020314/https://www.nist.gov/topics" class="usa-nav__link">All Topics</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/advanced-communications" class="usa-nav__link">Advanced communications</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/artificial-intelligence" class="usa-nav__link">Artificial intelligence</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/bioscience" class="usa-nav__link">Bioscience</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/buildings-construction" class="usa-nav__link">Buildings and construction</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/chemistry" class="usa-nav__link">Chemistry</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/climate" class="usa-nav__link">Climate</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/cybersecurity" class="usa-nav__link">Cybersecurity</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/electronics" class="usa-nav__link">Electronics</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/environment" class="usa-nav__link">Environment</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/fire" class="usa-nav__link">Fire</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/forensic-science" class="usa-nav__link">Forensic science</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/health" class="usa-nav__link">Health</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/information-technology" class="usa-nav__link">Information technology</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/infrastructure" class="usa-nav__link">Infrastructure</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/manufacturing" class="usa-nav__link">Manufacturing</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/materials" class="usa-nav__link">Materials</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/metrology" class="usa-nav__link">Metrology</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/nanotechnology" class="usa-nav__link">Nanotechnology</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/neutron-research" class="usa-nav__link">Neutron research</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/performance-excellence" class="usa-nav__link">Performance excellence</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/physics" class="usa-nav__link">Physics</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/public-safety" class="usa-nav__link">Public safety</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/resilience" class="usa-nav__link">Resilience</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/standards" class="usa-nav__link">Standards</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/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/20240117020314/https://www.nist.gov/laboratories" class="usa-nav__link">Laboratories</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240117020314/https://www.nist.gov/ctl" class="usa-nav__link">Communications Technology Laboratory</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/el" class="usa-nav__link">Engineering Laboratory</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/itl" class="usa-nav__link">Information Technology Laboratory</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/mml" class="usa-nav__link">Material Measurement Laboratory</a> </li> <li> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/user-facilities" class="usa-nav__link">User Facilities</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240117020314/https://www.nist.gov/ncnr" class="usa-nav__link">NIST Center for Neutron Research</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/cnst" class="usa-nav__link">CNST NanoFab</a> </li> </ul> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/laboratories/projects-programs" class="usa-nav__link">Research Projects</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/major-programs" class="usa-nav__link">Major Programs</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240117020314/https://www.nist.gov/baldrige" class="usa-nav__link">Baldrige Performance Excellence Program</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/chips" class="usa-nav__link">CHIPS for America Initiative</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/mep" class="usa-nav__link">Manufacturing Extension Partnership (MEP)</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/oam" class="usa-nav__link">Office of Advanced Manufacturing</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/spo" class="usa-nav__link">Special Programs Office</a> </li> <li> <a href="/web/20240117020314/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" 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/20240117020314/https://www.nist.gov/services-resources/standards-and-measurements" class="usa-nav__link">Standards and Measurements</a> <ul class="usa-nav__submenu-list"> <li> <a href="/web/20240117020314/https://www.nist.gov/calibrations" class="usa-nav__link">Calibration Services</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/nvlap" class="usa-nav__link">Laboratory Accreditation (NVLAP)</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/nist-quality-system" class="usa-nav__link">Quality System</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/srm" class="usa-nav__link">Standard Reference Materials (SRMs)</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/standardsgov" class="usa-nav__link">Standards.gov</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/pml/time-and-frequency-division/time-services" class="usa-nav__link">Time Services</a> </li> <li> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/services-resources/software" class="usa-nav__link">Software</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://webbook.nist.gov/chemistry/" class="usa-nav__link">Chemistry WebBook</a> </li> <li> <a href="https://web.archive.org/web/20240117020314/https://nvd.nist.gov/" class="usa-nav__link">National Vulnerability Database</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/pml/productsservices/physical-reference-data" class="usa-nav__link">Physical Reference Data</a> </li> <li> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/shop" class="usa-nav__link">Storefront</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://csrc.nist.gov/" class="usa-nav__link">Computer Security Resource Center (CSRC)</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/news-events/news" class="usa-nav__link">News</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/news-events/events" class="usa-nav__link">Events</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/blogs" class="usa-nav__link">Blogs</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/feature-stories" class="usa-nav__link">Feature Stories</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/video-gallery" class="usa-nav__link">Video Gallery</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/image-gallery" class="usa-nav__link">Image Gallery</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/about-nist" class="usa-nav__link">About Us</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/about-nist/visit" class="usa-nav__link">Visit</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/https://www.nist.gov/careers" class="usa-nav__link">Careers</a> </li> <li class="usa-nav__submenu-item"> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/director" class="usa-nav__link">Office of the Director</a> </li> <li> <a href="/web/20240117020314/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/20240117020314/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/20240117020314/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/20240117020314/http://nistdigitalarchives.contentdm.oclc.org/" class="usa-nav__link">NIST Digital Archives</a> </li> <li> <a href="/web/20240117020314/https://www.nist.gov/nist-museum" class="usa-nav__link">NIST Museum</a> </li> <li> <a href="/web/20240117020314/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/20240117020314/https://www.nist.gov/education" class="usa-nav__link">Educational Resources</a> </li> </ul> </div> </div> </div> </li> </ul> </div> </nav> </header>  </div> <div class="grid-container"> <div data-drupal-messages-fallback class="hidden"></div> </div> <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"> <div class="nist-page__region nist-page__region--content tablet-lg:grid-col-12"> <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="nist-page__region nist-page__region--content-top"> <div class="nist-block"> <a class="usa-button usa-button--accent-cool" href="/web/20240117020314/https://www.nist.gov/video-gallery">VIDEOS</a> </div> <div class="nist-block"> <h1 class="nist-page__title">What is a Standard Reference Material or SRM?</h1> </div> <div class="nist-block">  <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/20240117020314/https://www.facebook.com/share.php?u=https://www.nist.gov/video/what-standard-reference-material-or-srm" 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/20240117020314/https://www.linkedin.com/shareArticle?mini=true&url=https://www.nist.gov/video/what-standard-reference-material-or-srm&source=https://www.nist.gov/video/what-standard-reference-material-or-srm" 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/20240117020314/https://twitter.com/intent/tweet?url=https://www.nist.gov/video/what-standard-reference-material-or-srm&status=https://www.nist.gov/video/what-standard-reference-material-or-srm" title="Twitter" class="nist-social nist-social--twitter-gray"> <span>Twitter</span> </a> </div> <div> <a href="https://web.archive.org/web/20240117020314/mailto:/?subject=NIST.gov&body=Check out this site https://www.nist.gov/video/what-standard-reference-material-or-srm" title="Email" class="nist-social nist-social--envelope-gray"> <span>Email</span> </a> </div> </div> </div> </div>  </div> </div> </div> <div class="grid-container margin-top-4"> <div class="grid-row grid-gap-6"> <div class="nist-page__region nist-page__region--content tablet-lg:grid-col-8"> <div class="nist-block"> <div class="video-embed-field"><div class="video-embed-field-provider-nist-kaltura video-embed-field-responsive-video"><iframe width="854" height="480" frameborder="0" allow="autoplay *; fullscreen *; encrypted-media *" allowfullscreen="allowfullscreen" src="https://web.archive.org/web/20240117020314if_/https://www.kaltura.com/p/684682/sp/68468200/embedIframeJs/uiconf_id/31013851/partner_id/684682?iframeembed=true&entry_id=1_q0ew7l8z?iframeembed=true&entry_id=1_q0ew7l8z&flashvars%5BautoPlay%5D=1"></iframe> </div> </div> </div> <div class="nist-block"> <h2 class="nist-block__title">Appears In</h2> <ul><li><a href="/web/20240117020314/https://www.nist.gov/feature-stories/why-you-need-standards/standard-reference-materials">Standard Reference Materials</a></li></ul> </div> </div> <aside class="nist-page__region nist-page__region--sidebar-second tablet-lg:grid-col-4"> <div> <div class="nist-block"> <div class="nist-video__caption">How do you know if the numbers in your lab results or your food's nutritional labels are correct? Labs and manufacturers use Standard Reference Materials or SRMs to make sure that the machines measuring these numbers are accurate. Learn what SRMs are in this animated explainer. For more information go to www.nist.gov/srm</div> </div> <div class="nist-block"> <div class="nist-field nist-field--label-inline datetime"> <div class="nist-field__label">Uploaded On</div> <div class="nist-field__item"><time datetime="2022-11-02T23:23:04Z">November 2, 2022</time> </div> </div> </div> </div> </aside> </div> </div> <div class="grid-container"> </div> </section> </div> </div> </div> </div> <div class="grid-container"> </div> </section> <div data-elastic-exclude>  <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/20240117020314/https://www.nist.gov/" title="National Institute of Standards and Technology" rel="home"> <img class="nist-footer__logo-img" src="/web/20240117020314im_/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/20240117020314/tel:301-975-2000">301-975-2000</a> </address> <p> <a href="https://web.archive.org/web/20240117020314/mailto:do-webmaster@nist.gov">Webmaster</a> | <a href="https://web.archive.org/web/20240117020314/https://www.nist.gov/about-nist/contact-us">Contact Us</a> | <a href="https://web.archive.org/web/20240117020314/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/20240117020314/https://twitter.com/NIST"> <span>Twitter</span> </a> <a class="nist-social nist-social--facebook-white" href="https://web.archive.org/web/20240117020314/https://www.facebook.com/NIST"> <span>Facebook</span> </a> <a class="nist-social nist-social--linkedin-white" href="https://web.archive.org/web/20240117020314/https://www.linkedin.com/company/nist"> <span>LinkedIn</span> </a> <a class="nist-social nist-social--instagram-white" href="https://web.archive.org/web/20240117020314/https://www.instagram.com/nist/"> <span>Instagram</span> </a> <a class="nist-social nist-social--youtube-white" href="https://web.archive.org/web/20240117020314/https://www.youtube.com/NIST"> <span>YouTube</span> </a> <a class="nist-social nist-social--giphy-white" href="https://web.archive.org/web/20240117020314/https://giphy.com/nist"> <span>Giphy</span> </a> <a class="nist-social nist-social--rss-white" href="https://web.archive.org/web/20240117020314/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/20240117020314/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/20240117020314/https://www.nist.gov/form/nist-gov-feedback?destination=/video/what-standard-reference-material-or-srm" 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/20240117020314/https://www.nist.gov/privacy-policy">Site Privacy</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/https://www.nist.gov/oism/accessibility">Accessibility</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/https://www.nist.gov/privacy">Privacy Program</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/https://www.nist.gov/oism/copyrights">Copyrights</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/https://www.commerce.gov/vulnerability-disclosure-policy">Vulnerability Disclosure</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/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/20240117020314/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/20240117020314/https://www.nist.gov/environmental-policy-statement">Environmental Policy</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/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/20240117020314/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/20240117020314/https://www.commerce.gov/">Commerce.gov</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/http://www.science.gov/">Science.gov</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/http://www.usa.gov/">USA.gov</a> </li> <li class="nist-footer__menu-item"> <a href="https://web.archive.org/web/20240117020314/https://vote.gov/">Vote.gov</a> </li> </ul> </div> </div> </footer>  </div> </div> <script type="application/json" data-drupal-selector="drupal-settings-json">{"path":{"baseUrl":"\/","scriptPath":null,"pathPrefix":"","currentPath":"media\/658051","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":"","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":"append","extFaLinkClasses":"fa fa-external-link","extFaMailtoClasses":"fa fa-envelope-o","whitelistedDomains":[]}},"user":{"uid":0,"permissionsHash":"2f77e4dcfce20728ac491170886da836c10b580f9bdfeb9c9e729fe4958834d5"}}</script> <script src="/web/20240117020314js_/https://www.nist.gov/sites/default/files/js/js_p8gamLXxPBoNiUHgUZaxT5BzySkZcDUazIUKuriGtWc.js?scope=footer&delta=0&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"></script> <script src="https://web.archive.org/web/20240117020314js_/https://siteimproveanalytics.com/js/siteanalyze_6017546.js" async></script> <script src="/web/20240117020314js_/https://www.nist.gov/sites/default/files/js/js_UGmxJmd0KTfzVgunMIRinV6JOK7saYPAZ8EHmjYWKVY.js?scope=footer&delta=2&language=en&theme=nist_www&include=eJx1kOFuwyAMhF-IlkdCDlypW8AM02R5-4WsVaNOk_jh-3yyD3tpsLevB9pqJvJ312V71R5qd9N_W-ylmCgSExwVSmtnr_YTmMLaXeJy5-4unDqa_YtcpF-jcgfn2mSG_QQjzM76FRlbBkkTNZcl2MBK07Z2DDW6akfesip2v41JJkrH-vQcZa-ggPaSblmWo_ughwXffSywoT0qpfNTmpkDxCFPCNt3kIJt0CpFecZpbxoVz5RcRmAawdgb_77-WYqHuXD0VDtLed3pTX4Aki2oVQ"></script> <script type="text/javascript">window.NREUM||(NREUM={});NREUM.info={"beacon":"gov-bam.nr-data.net","licenseKey":"37b7ccb661","applicationID":"1089704227","transactionName":"YFxUN0sADEdYVkBaClkWdwBNCA1aFkVVVABoWlcAUQQ=","queueTime":4,"applicationTime":29,"atts":"TBtXQQMaH0k=","errorBeacon":"gov-bam.nr-data.net","agent":""}</script></body> </html>

CINXE.COM

What is a Standard Reference Material or SRM? | NIST