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 <div class="section">
 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
 <a name="id-1.2.4.3"></a>Terminology</h2></div></div></div>
 <p>

     </p>
 <div class="variablelist"><table border="0" class="variablelist">
 <colgroup>
 <col align="left" valign="top">
 <col>
 </colgroup>
 <tbody>
 <tr>
 <td><p><span class="term">script</span></p></td>
 <td>
 <p>
 	      In text shaping, a <span class="emphasis"><em>script</em></span> is a
 	      writing system: a set of symbols, rules, and conventions
 	      that is used to represent a language or multiple
 	      languages.
 	    </p>
 <p>
 	      In general computing lingo, the word "script" can also
 	      be used to mean an executable program (usually one
 	      written in a human-readable programming language). For
 	      the sake of clarity, HarfBuzz documents will always use
 	      more specific terminology when referring to this
 	      meaning, such as "Python script" or "shell script." In
 	      all other instances, "script" refers to a writing system.
 	    </p>
 <p>
 	      For developers using HarfBuzz, it is important to note
 	      the distinction between a script and a language. Most
 	      scripts are used to write a variety of different
 	      languages, and many languages may be written in more
 	      than one script.
 	    </p>
 </td>
 </tr>
 <tr>
 <td><p><span class="term">shaper</span></p></td>
 <td><p>
 	      In HarfBuzz, a <span class="emphasis"><em>shaper</em></span> is a
 	      handler for a specific script-shaping model. HarfBuzz
 	      implements separate shapers for Indic, Arabic, Thai and
 	      Lao, Khmer, Myanmar, Tibetan, Hangul, Hebrew, the
 	      Universal Shaping Engine (USE), and a default shaper for
 	      non-complex scripts.
 	    </p></td>
 </tr>
 <tr>
 <td><p><span class="term">cluster</span></p></td>
 <td>
 <p>
 	      In text shaping, a <span class="emphasis"><em>cluster</em></span> is a
 	      sequence of codepoints that must be treated as an
 	      indivisible unit. Clusters can include code-point
 	      sequences that form a ligature or base-and-mark
 	      sequences. Tracking and preserving clusters is important
 	      when shaping operations might separate or reorder
 	      code points.
 	    </p>
 <p>
 	      HarfBuzz provides three cluster
 	      <span class="emphasis"><em>levels</em></span> that implement different
 	      approaches to the problem of preserving clusters during
 	      shaping operations.
 	    </p>
 </td>
 </tr>
 <tr>
 <td><p><span class="term">grapheme</span></p></td>
 <td>
 <p>
 	      In linguistics, a <span class="emphasis"><em>grapheme</em></span> is one
 	      of the indivisible units that make up a writing system or
 	      script. Often, graphemes are individual symbols (letters,
 	      numbers, punctuation marks, logograms, etc.) but,
 	      depending on the writing system, a particular grapheme
 	      might correspond to a sequence of several Unicode code
 	      points.
 	    </p>
 <p>
 	      In practice, HarfBuzz and other text-shaping engines
 	      are not generally concerned with graphemes. However, it
 	      is important for developers using HarfBuzz to recognize
 	      that there is a difference between graphemes and shaping
 	      clusters (see above). The two concepts may overlap
 	      frequently, but there is no guarantee that they will be
 	      identical.
 	    </p>
 </td>
 </tr>
 <tr>
 <td><p><span class="term">syllable</span></p></td>
 <td>
 <p>
 	      In linguistics, a <span class="emphasis"><em>syllable</em></span> is an
 	      a sequence of sounds that makes up a building block of a
 	      particular language. Every language has its own set of
 	      rules describing what constitutes a valid syllable.
 	    </p>
 <p>
 	      For text-shaping purposes, the various definitions of
 	      "syllable" are important because script-specific shaping
 	      operations may be applied at the syllable level. For
 	      example, a reordering rule might specify that a vowel
 	      mark be reordered to the beginning of the syllable.
 	    </p>
 <p>
 	      Syllables will consist of one or more Unicode code
 	      points. The definition of a syllable for a particular
 	      writing system might correspond to how HarfBuzz
 	      identifies clusters (see above) for the same writing
 	      system. However, it is important for developers using
 	      HarfBuzz to recognize that there is a difference between
 	      syllables and shaping clusters. The two concepts may
 	      overlap frequently, but there is no guarantee that they
 	      will be identical.
 	    </p>
 </td>
 </tr>
 </tbody>
 </table></div>
 </div>
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	<title>Terminology: HarfBuzz Manual</title>
	<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
	<link rel="home" href="index.html" title="HarfBuzz Manual">
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	<table class="navigation" id="top" width="100%" summary="Navigation header" cellpadding="2" cellspacing="5"><tr valign="middle">
	<td width="100%" align="left" class="shortcuts"></td>
	<td><a accesskey="h" href="index.html"><img src="home.png" width="16" height="16" border="0" alt="Home"></a></td>
	<td><a accesskey="u" href="getting-started.html"><img src="up.png" width="16" height="16" border="0" alt="Up"></a></td>
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	<div class="section">
	<div class="titlepage"><div><div><h2 class="title" style="clear: both">
	<a name="id-1.2.4.3"></a>Terminology</h2></div></div></div>
	<p>

	</p>
	<div class="variablelist"><table border="0" class="variablelist">
	<colgroup>
	<col align="left" valign="top">
	<col>
	</colgroup>
	<tbody>
	<tr>
	<td><p><span class="term">script</span></p></td>
	<td>
	<p>
	In text shaping, a <span class="emphasis"><em>script</em></span> is a
	writing system: a set of symbols, rules, and conventions
	that is used to represent a language or multiple
	languages.
	</p>
	<p>
	In general computing lingo, the word "script" can also
	be used to mean an executable program (usually one
	written in a human-readable programming language). For
	the sake of clarity, HarfBuzz documents will always use
	more specific terminology when referring to this
	meaning, such as "Python script" or "shell script." In
	all other instances, "script" refers to a writing system.
	</p>
	<p>
	For developers using HarfBuzz, it is important to note
	the distinction between a script and a language. Most
	scripts are used to write a variety of different
	languages, and many languages may be written in more
	than one script.
	</p>
	</td>
	</tr>
	<tr>
	<td><p><span class="term">shaper</span></p></td>
	<td><p>
	In HarfBuzz, a <span class="emphasis"><em>shaper</em></span> is a
	handler for a specific script-shaping model. HarfBuzz
	implements separate shapers for Indic, Arabic, Thai and
	Lao, Khmer, Myanmar, Tibetan, Hangul, Hebrew, the
	Universal Shaping Engine (USE), and a default shaper for
	non-complex scripts.
	</p></td>
	</tr>
	<tr>
	<td><p><span class="term">cluster</span></p></td>
	<td>
	<p>
	In text shaping, a <span class="emphasis"><em>cluster</em></span> is a
	sequence of codepoints that must be treated as an
	indivisible unit. Clusters can include code-point
	sequences that form a ligature or base-and-mark
	sequences. Tracking and preserving clusters is important
	when shaping operations might separate or reorder
	code points.
	</p>
	<p>
	HarfBuzz provides three cluster
	<span class="emphasis"><em>levels</em></span> that implement different
	approaches to the problem of preserving clusters during
	shaping operations.
	</p>
	</td>
	</tr>
	<tr>
	<td><p><span class="term">grapheme</span></p></td>
	<td>
	<p>
	In linguistics, a <span class="emphasis"><em>grapheme</em></span> is one
	of the indivisible units that make up a writing system or
	script. Often, graphemes are individual symbols (letters,
	numbers, punctuation marks, logograms, etc.) but,
	depending on the writing system, a particular grapheme
	might correspond to a sequence of several Unicode code
	points.
	</p>
	<p>
	In practice, HarfBuzz and other text-shaping engines
	are not generally concerned with graphemes. However, it
	is important for developers using HarfBuzz to recognize
	that there is a difference between graphemes and shaping
	clusters (see above). The two concepts may overlap
	frequently, but there is no guarantee that they will be
	identical.
	</p>
	</td>
	</tr>
	<tr>
	<td><p><span class="term">syllable</span></p></td>
	<td>
	<p>
	In linguistics, a <span class="emphasis"><em>syllable</em></span> is an
	a sequence of sounds that makes up a building block of a
	particular language. Every language has its own set of
	rules describing what constitutes a valid syllable.
	</p>
	<p>
	For text-shaping purposes, the various definitions of
	"syllable" are important because script-specific shaping
	operations may be applied at the syllable level. For
	example, a reordering rule might specify that a vowel
	mark be reordered to the beginning of the syllable.
	</p>
	<p>
	Syllables will consist of one or more Unicode code
	points. The definition of a syllable for a particular
	writing system might correspond to how HarfBuzz
	identifies clusters (see above) for the same writing
	system. However, it is important for developers using
	HarfBuzz to recognize that there is a difference between
	syllables and shaping clusters. The two concepts may
	overlap frequently, but there is no guarantee that they
	will be identical.
	</p>
	</td>
	</tr>
	</tbody>
	</table></div>
	</div>
	<div class="footer">
	<hr>Generated by GTK-Doc V1.25</div>
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