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<document>
  <header>
    <title>Apache™ FOP: Complex Scripts</title>
  </header>
  <body>
    <section id="overview">
      <title>Overview</title>
      <p>
        This page describes the
        <a href="http://en.wikipedia.org/wiki/Complex_scripts">complex scripts</a>
        features of Apache™ FOP, which include:
      </p>
      <ul>
        <li>Support for languages written with right-to-left scripts, such as Arabic and Hebrew scripts.</li>
        <li>Support for languages written with South Asian and Southeast Asian scripts, such as Devanagari,
          Khmer, Tamil, Thai, and others.</li>
        <li>Support for advanced substitution, reordering, and positioning of glyphs according to language
          and script sensitive rules.</li>
        <li>Support for advanced number to string formatting.</li>
      </ul>
    </section>
    <section>
      <title>Disabling complex scripts</title>
      <p>Complex script features are enabled by default. If some application of FOP does not
         require this support, then it can be disabled in three ways:</p>
      <ol>
        <li>
          <strong>Command line:</strong> The command line option <code>-nocs</code> turns off complex script
          features: <code>fop -nocs -fo mydocument.fo -pdf mydocument.pdf</code>            
        </li>
        <li>
          <strong>Embedding:</strong> <code>userAgent.setComplexScriptFeaturesEnabled(false);</code>
        </li>
        <li>
          <strong>Optional setting in fop.xconf file:</strong>
          <pre>
&lt;fop version="1.0"&gt;
  &lt;complex-scripts disabled="true"/&gt;
  ...
&lt;/fop&gt;
          </pre>
        </li>
      </ol>
      <p>
        When complex scripts features are enabled, additional information related to bidirectional
        level resolution, the association between characters and glyphs, and glyph position adjustments
        are added to the internal, parsed representation of the XSL-FO tree and its corresponding
        formatted area tree. This additional information will somewhat increase the memory requirements for
        processing documents that use these features.
      </p>
      <note>A document author need not make explicit use of any complex scripts feature in order
        for this additional information to be created. For example, if the author makes use of a font
        that contains OpenType GSUB and/or GPOS tables, then those tables will be automatically used
        unless complex scripts features are disabled.</note>
    </section>
    <section id="source">
      <title>Changes to your XSL-FO input files</title>
      <p>
        In most circumstances, XSL-FO content does not need to change in order to make use of
        complex scripts features; however, in certain contexts, fully automatic processing is not
        sufficient. In these cases, an author may make use of the following XSL-FO constructs:
      </p>
      <ul>
        <li>The <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#script"><code>script</code></a> property.</li>
        <li>The <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#language"><code>language</code></a> property.</li>
        <li>The <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#writing-mode"><code>writing-mode</code></a> property.</li>
        <li>The number to string conversion properties:
          <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#format"><code>format</code></a>,
          <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#grouping-separator"><code>grouping-separator</code></a>,
          <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#grouping-size"><code>grouping-size</code></a>,
          <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#letter-value"><code>letter-value</code></a>,
          and <code>fox:number-conversion-features</code>.</li>
        <li>The <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#fo_bidi-override"><code>fo:bidi-override</code></a> element.</li>
        <li>Explicit bidirectional control characters: U+200E LRM, U+200F RLM, U+202A LRE,
          U+202B RLE, U+202C PDF, U+202D LRO, U+202E RLO.</li>
        <li>Explicit join control characters: U+200C ZWNJ and U+200D ZWJ.</li>
      </ul>
    </section>
    <section id="details">
      <title>Authoring Details</title>
      <p>The complex scripts related effects of the above enumerated XSL-FO constructs are more
        fully described in the following sub-sections.</p>
      <section id="script_property">
        <title>Script Property</title>
        <p>In order to apply font specific complex script features, it is necessary to know
          the script that applies to the text undergoing layout processing. This script is determined
          using the following algorithm:
        </p>
        <ol>
          <li>If the FO element that governs the text specifies a
            <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#script"><code>script</code></a>
            property and its value is not the empty string or <code>"auto"</code>, then that script is used.</li>
          <li>Otherwise, the dominant script of the text is determined automatically by finding the
            script whose constituent characters appear most frequently in the text.</li>
        </ol>
        <p>In case the automatic algorithm does not produce the desired results, an author may
          explicitly specify a <code>script</code> property with the desired script. If specified,
          it must be one of the four-letter script code specified in
          <a href="http://unicode.org/iso15924/iso15924-codes.html">ISO 15924 Code List</a> or
          in the <a href="#extended_script_codes">Extended Script Codes</a> table.  Comparison
          of script codes is performed in a case-insensitive manner, so it does not matter what case
          is used when specifying these codes in an XSL-FO document.</p>
        <section id="standard_script_codes">
          <title>Standard Script Codes</title>
          <p>The following table enumerates the standard ISO 15924 4-letter codes recognized by FOP.</p>
          <table class="ForrestTable tw30">
            <tr>
              <th style="text-align:center">Code</th>
              <th style="text-align:left">Script</th>
            </tr>
            <tr>
              <td style="text-align:center"><code>arab</code></td>
              <td>Arabic</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>beng</code></td>
              <td>Bengali</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>bopo</code></td>
              <td>Bopomofo</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>cyrl</code></td>
              <td>Cyrillic</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>deva</code></td>
              <td>Devanagari</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>ethi</code></td>
              <td>Ethiopic</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>geor</code></td>
              <td>Georgian</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>grek</code></td>
              <td>Greek</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>gujr</code></td>
              <td>Gujarati</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>guru</code></td>
              <td>Gurmukhi</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>hang</code></td>
              <td>Hangul</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>hani</code></td>
              <td>Han</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>hebr</code></td>
              <td>Hebrew</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>hira</code></td>
              <td>Hiragana</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>kana</code></td>
              <td>Katakana</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>knda</code></td>
              <td>Kannada</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>khmr</code></td>
              <td>Khmer</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>laoo</code></td>
              <td>Lao</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>latn</code></td>
              <td>Latin</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>mlym</code></td>
              <td>Malayalam</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>mymr</code></td>
              <td>Burmese</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>mong</code></td>
              <td>Mongolian</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>orya</code></td>
              <td>Oriya</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>sinh</code></td>
              <td>Sinhalese</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>taml</code></td>
              <td>Tamil</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>telu</code></td>
              <td>Telugu</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>thai</code></td>
              <td>Thai</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>tibt</code></td>
              <td>Tibetan</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>zmth</code></td>
              <td>Math</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>zsym</code></td>
              <td>Symbol</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>zyyy</code></td>
              <td>Undetermined</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>zzzz</code></td>
              <td>Uncoded</td>
            </tr>
          </table>
        </section>
        <section id="extended_script_codes">
          <title>Extended Script Codes</title>
          <p>The following table enumerates a number of non-standard extended script codes recognized by FOP.</p>
          <table class="ForrestTable tw70">
            <colgrp>
              <col style="width:10%"/>
              <col style="width:20%"/>
              <col style="width:80%"/>
            </colgrp>
            <tr>
              <th>Code</th>
              <th>Script</th>
              <th>Comments</th>
            </tr>
            <tr>
              <td style="text-align:center"><code>bng2</code></td>
              <td>Bengali</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>dev2</code></td>
              <td>Devanagari</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>gur2</code></td>
              <td>Gurmukhi</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>gjr2</code></td>
              <td>Gujarati</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>knd2</code></td>
              <td>Kannada</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>mlm2</code></td>
              <td>Malayalam</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>ory2</code></td>
              <td>Oriya</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>tml2</code></td>
              <td>Tamil</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
            <tr>
              <td style="text-align:center"><code>tel2</code></td>
              <td>Telugu</td>
              <td>OpenType Indic Version 2 (May 2008 and following) behavior.</td>
            </tr>
          </table>
          <warning>
            Explicit use of one of the above extended script codes is not portable,
            and should be limited to use with FOP only.
          </warning>
          <note>
            When performing automatic script determination, FOP selects the OpenType Indic
            Version 2 script codes by default. If the author requires Version 1 behavior, then
            an explicit, non-extension script code should be specified in a governing <code>script</code>
            property.
          </note>
        </section>
      </section>
      <section id="language_property">
        <title>Language Property</title>
        <p>Certain fonts that support complex script features can make use of language information in order for
          language specific processing rules to be applied. For example, a font designed for the Arabic script may support
          typographic variations according to whether the written language is Arabic, Farsi (Persian), Sindhi, Urdu, or
          another language written with the Arabic script. In order to apply these language specific features, the author
          may explicitly mark the text with a <a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#language"><code>language</code></a>
          property.</p>
        <p>When specifying the <code>language</code> property, the value of the property must be either an
          <a href="http://en.wikipedia.org/wiki/List_of_ISO_639-2_codes">ISO639-2 3-letter code</a> or an
          <a href="http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes">ISO639-1 2-letter code</a>.  Comparison of language
          codes is performed in a case-insensitive manner, so it does not matter what case is used when specifying these
          codes in an XSL-FO document.</p>
      </section>
      <section id="writing_mode_property">
        <title>Writing Mode Property</title>
      </section>
      <section id="number_conversion_properties">
        <title>Number Conversion Properties</title>
      </section>
      <section id="bidi_override_element">
        <title>Bidi Override Element</title>
      </section>
      <section id="bidi_controls">
        <title>Bidi Control Characters</title>
      </section>
      <section id="join_controls">
        <title>Join Control Characters</title>
      </section>
    </section>
    <section id="supported_scripts">
      <title>Supported Scripts</title>
      <p>Support for specific complex scripts is enumerated in the following table. Support
        for those marked as not being supported is expected to be added in future revisions.</p>
      <table>
        <colgrp>
          <col style="width: 15%"/>
          <col style="width: 10%"/>
          <col style="width: 10%"/>
          <col style="width: 65%"/>
        </colgrp>
        <tr>
          <th style="text-align:left">Script</th>
          <th>Support</th>
          <th>Tested</th>
          <th style="text-align:left">Comments</th>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Arabic_alphabet">Arabic</a></td>
          <td class="yes">full</td>
          <td class="yes">full</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Bengali_alphabet">Bengali</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Burmese_alphabet">Burmese</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Devanagari_alphabet">Devanagari</a></td>
          <td class="partial">partial</td>
          <td class="partial">partial</td>
          <td style="text-align:left">join controls (ZWJ, ZWNJ) not yet supported</td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Khmer_alphabet">Khmer</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Gujarati_alphabet">Gujarati</a></td>
          <td class="partial">partial</td>
          <td class="no">none</td>
          <td style="text-align:left">pre-alpha</td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Gurmukhī_alphabet">Gurmukhi</a></td>
          <td class="partial">partial</td>
          <td class="no">none</td>
          <td style="text-align:left">pre-alpha</td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Hebrew_alphabet">Hebrew</a></td>
          <td class="yes">full</td>
          <td class="partial">partial</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Kannada_alphabet">Kannada</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Lao_alphabet">Lao</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Malayalam_alphabet">Malayalam</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Mongolian_script">Mongolian</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Oriya_script">Oriya</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Tamil_alphabet">Tamil</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Telugu_alphabet">Telugu</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Tibetan_alphabet">Tibetan</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
        <tr>
          <td><a href="http://en.wikipedia.org/wiki/Thai_alphabet">Thai</a></td>
          <td class="no">none</td>
          <td class="no">none</td>
          <td></td>
        </tr>
      </table>
    </section>
    <section id="supported_fonts">
      <title>Supported Fonts</title>
      <p>Support for specific fonts is enumerated in the following sub-sections. If a given
        font is not listed, then it has not been tested with these complex scripts features.</p>
      <section id="fonts_arabic">
        <title>Arabic Fonts</title>
        <table>
          <colgrp>
            <col style="width: 15%"/>
            <col style="width: 10%"/>
            <col style="width: 10%"/>
            <col style="width: 65%"/>
          </colgrp>
          <tr>
            <th style="text-align:left">Font</th>
            <th style="text-align:left">Version</th>
            <th style="text-align:center">Glyphs</th>
            <th style="text-align:left">Comments</th>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=24">Arial Unicode MS</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1081">1.01</a></td>
            <td style="text-align:center">50377</td>
            <td>limited GPOS support</td>
          </tr>
          <tr>
            <td><a href="http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&amp;id=ArabicFonts">Lateef</a></td>
            <td class="yes" style="text-align:left">1.0</td>
            <td style="text-align:center">1147</td>
            <td>language features for Kurdish (KUR), Sindhi (SND), Urdu (URD)</td>
          </tr>
          <tr>
            <td><a href="http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&amp;id=ArabicFonts">Scheherazade</a></td>
            <td class="yes" style="text-align:left">1.0</td>
            <td style="text-align:center">1197</td>
            <td>language features for Kurdish (KUR), Sindhi (SND), Urdu (URD)</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=261">Simplified Arabic</a></td>
            <td class="no" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=867">1.01</a></td>
            <td/>
            <td>contains invalid, out of order coverage table entries</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/font.aspx?FID=261">Simplified Arabic</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1645">5.00</a></td>
            <td style="text-align:center">414</td>
            <td>lacks GPOS support</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/font.aspx?FID=261">Simplified Arabic</a></td>
            <td class="yes" style="text-align:left">5.92</td>
            <td style="text-align:center">473</td>
            <td>includes GPOS for advanced position adjustment</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=264">Traditional Arabic</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/family.aspx?FMID=877">1.01</a></td>
            <td style="text-align:center">530</td>
            <td>lacks GPOS support</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/font.aspx?FID=264">Traditional Arabic</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1658">5.00</a></td>
            <td style="text-align:center">530</td>
            <td>lacks GPOS support</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/font.aspx?FID=264">Traditional Arabic</a></td>
            <td class="yes" style="text-align:left">5.92</td>
            <td style="text-align:center">589</td>
            <td>includes GPOS for advanced position adjustment</td>
          </tr>
        </table>
      </section>
      <section id="devanagari_fonts">
        <title>Devanagari Fonts</title>
        <table>
          <colgrp>
            <col style="width: 15%"/>
            <col style="width: 10%"/>
            <col style="width: 10%"/>
            <col style="width: 65%"/>
          </colgrp>
          <tr>
            <th style="text-align:left">Font</th>
            <th style="text-align:left">Version</th>
            <th style="text-align:center">Glyphs</th>
            <th style="text-align:left">Comments</th>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=370">Aparajita</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1700">1.00</a></td>
            <td style="text-align:center">706</td>
            <td/>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=374">Kokila</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1749">1.00</a></td>
            <td style="text-align:center">706</td>
            <td/>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=243">Mangal</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1759">5.01</a></td>
            <td style="text-align:center">885</td>
            <td>designed for use in user interfaces</td>
          </tr>
          <tr>
            <td><a href="http://www.microsoft.com/typography/fonts/family.aspx?FID=384">Utsaah</a></td>
            <td class="yes" style="text-align:left"><a href="http://www.microsoft.com/typography/fonts/font.aspx?FMID=1811">1.00</a></td>
            <td style="text-align:center">706</td>
            <td/>
          </tr>
        </table>
      </section>
    </section>
    <section id="limitations">
      <title>Other Limitations</title>
      <p>
        Complex scripts support in Apache FOP is relatively new, so there are certain
        limitations. Please help us identify and close any gaps.
      </p>
      <ul>
        <li>Only the PDF output format fully supports complex scripts features at the present time.</li>
        <li>Shaping context does not extend across an element boundary. This limitation prevents the use of
        <code>fo:character</code>, <code>fo:inline</code> or <code>fo:wrapper</code> in order to colorize
        individual Arabic letters without affecting shaping behavior across the element boundary.</li>
      </ul>
    </section>
    <section id="links">
      <title>Related Links</title>
      <p>
        In addition to the XSL-FO specification, a number of external resources provide
        guidance about authoring documents that employ complex scripts and the features
        described above:
      </p>
      <ul>
        <li><a href="http://www.unicode.org/">The Unicode Standard</a></li>
        <li><a href="http://www.w3.org/TR/2006/REC-xsl11-20061205/#fo_bidi-override">Unicode Bidirectional Algorithm</a></li>
        <li><a href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType Advanced Typographic Extensions</a></li>
        <li><a href="http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&amp;item_id=CmplxRndExamples">Examples of Complex Rendering</a></li>
      </ul>
    </section>
  </body>
</document>
