<h1>Why do my user defined symbols (e.g., <tt>\i, \l, \L, \o, \ae,</tt> etc.) display incorrectly in the processed document?</h1> <p> By default, our system processes documents using <a href="http://arXiv.org/hypertex">HyperTeX</a>, which includes the <tt>pd1enc.def</tt> macro. Since the macro is called late in the preamble, it will overwrite previous definitions, including author defined single character definitions using <tt>\i, \l, \o, \ae,</tt> and some common composites: </p> <pre> \DeclareTextCommand{\L}{PD1}{L} % Lslash, \225 \DeclareTextCommand{\OE}{PD1}{\226} % OE \DeclareTextCommand{\IJ}{PD1}{\230} \DeclareTextCommand{\i}{PD1}{i} % dotlessi, \232 \DeclareTextCommand{\l}{PD1}{l} % lslash, \233 \DeclareTextCommand{\oe}{PD1}{\234} % oe \DeclareTextCommand{\AE}{PD1}{\306} % AE \DeclareTextCommand{\DH}{PD1}{\320} % Eth \DeclareTextCommand{\DJ}{PD1}{\320} % Eth \DeclareTextCommand{\O}{PD1}{\330} % Oslash \DeclareTextCommand{\TH}{PD1}{\336} % Thorn \DeclareTextCommand{\ss}{PD1}{\337} % germandbls \DeclareTextCommand{\ae}{PD1}{\346} % ae \DeclareTextCommand{\dh}{PD1}{\360} % eth \DeclareTextCommand{\o}{PD1}{\370} % oslash \DeclareTextCommand{\th}{PD1}{\376} % thorn \DeclareTextCommand{\ij}{PD1}{\377} \DeclareTextCommand{\SS}{PD1}{SS} </pre> To circumvent this problem, you should either avoid using the abbreviations above, or <a href="http://arxiv.org/help/faq/mistakes#nohypertex">disable HyperTeX</a>.