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Presentation semantics
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<p>In <a href="/facts/Computer_science/lN3pEyPz">computer science</a>, particularly in <a href="/facts/Human-computer_interaction/EkmIxGCx">human-computer interaction</a>, presentation semantics specify how a particular piece of a <a href="/facts/Formal_language/crDTyP8q">formal language</a> is represented in a distinguished manner accessible to <a href="/facts/Human_senses/n9kYQ3rf">human senses</a>, usually human vision. For example, saying that <bold> ... </bold> must render the text between these constructs using some <a href="/facts/Bold_typeface/RXGfXwcG">bold typeface</a> is a specification of presentation semantics for that <a href="/facts/Syntax/6PxSV98p">syntax</a>. </p><p>Many <a href="/facts/Markup_languages/WwhlNVIu">markup languages</a>, including <a href="/facts/HTML/sSc3fT78">HTML</a>, <a href="/facts/DSSSL/2NUdj7KC">DSSSL</a>, and <a href="/facts/XSL-FO/zknLahV3">XSL-FO</a>, have presentation semantics, but others, such as <a href="/facts/XML/clNgUfWk">XML</a>, do not. <a href="/facts/Character_encoding/ShJHIMoA">Character encoding</a> standards, such as <a href="/facts/Unicode/DDu3MfPV">Unicode</a>, also have presentation semantics. </p><p>One of the main goals of <a href="/facts/Style_sheet_language/sAU6MR9u">style sheet languages</a> is to separate the syntax that defines document content from the syntax endowed with presentation semantics. This is the norm on the <a href="/facts/World_Wide_Web/wvnTrWFq">World Wide Web</a>, where the <a href="/facts/Cascading_Style_Sheets/tA90XBQo">Cascading Style Sheets</a> language provides a large collection of presentation semantics for HTML documents. </p>