192 lines
8.4 KiB
XML
192 lines
8.4 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="glXUseXFont">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glXUseXFont</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glXUseXFont</refname>
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<refpurpose>create bitmap display lists from an X font</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glXUseXFont</function></funcdef>
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<paramdef>Font <parameter>font</parameter></paramdef>
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<paramdef>int <parameter>first</parameter></paramdef>
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<paramdef>int <parameter>count</parameter></paramdef>
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<paramdef>int <parameter>listBase</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<!-- eqn: ignoring delim $$ -->
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>font</parameter></term>
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<listitem>
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<para>
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Specifies the font from which character glyphs are to be taken.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>first</parameter></term>
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<listitem>
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<para>
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Specifies the index of the first glyph to be taken.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>count</parameter></term>
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<listitem>
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<para>
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Specifies the number of glyphs to be taken.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>listBase</parameter></term>
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<listitem>
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<para>
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Specifies the index of the first display list to be generated.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para>
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<function>glXUseXFont</function> generates <parameter>count</parameter> display lists,
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named <parameter>listBase</parameter> through
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<inlineequation><mml:math>
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<!-- eqn: listBase + count - 1:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">listBase</mml:mi>
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<mml:mo>+</mml:mo>
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<mml:mi mathvariant="italic">count</mml:mi>
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<mml:mo>-</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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</mml:math></inlineequation>,
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each containing a single <citerefentry><refentrytitle>glBitmap</refentrytitle></citerefentry> command.
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The parameters of the <citerefentry><refentrytitle>glBitmap</refentrytitle></citerefentry> command of display list
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<inlineequation><mml:math>
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<!-- eqn: listBase + i:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">listBase</mml:mi>
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<mml:mo>+</mml:mo>
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<mml:mi mathvariant="italic">i</mml:mi>
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</mml:mrow>
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</mml:math></inlineequation>
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are derived from glyph
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<inlineequation><mml:math>
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<!-- eqn: first + i:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">first</mml:mi>
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<mml:mo>+</mml:mo>
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<mml:mi mathvariant="italic">i</mml:mi>
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</mml:mrow>
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</mml:math></inlineequation>.
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Bitmap parameters
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<inlineequation><mml:math><mml:mi mathvariant="italic">xorig</mml:mi></mml:math></inlineequation>,
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<inlineequation><mml:math><mml:mi mathvariant="italic">yorig</mml:mi></mml:math></inlineequation>,
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<inlineequation><mml:math><mml:mi mathvariant="italic">width</mml:mi></mml:math></inlineequation>,
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and
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<inlineequation><mml:math><mml:mi mathvariant="italic">height</mml:mi></mml:math></inlineequation>
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are computed from font metrics as
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<inlineequation><mml:math>
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<!-- eqn: descent-1:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">descent</mml:mi>
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<mml:mo>-</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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</mml:math></inlineequation>,
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<inlineequation><mml:math>
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<!-- eqn: -lbearing:-->
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<mml:mrow>
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<mml:mo>-</mml:mo>
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<mml:mi mathvariant="italic">lbearing</mml:mi>
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</mml:mrow>
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</mml:math></inlineequation>,
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<inlineequation><mml:math>
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<!-- eqn: rbearing - lbearing:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">rbearing</mml:mi>
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<mml:mo>-</mml:mo>
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<mml:mi mathvariant="italic">lbearing</mml:mi>
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</mml:mrow>
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</mml:math></inlineequation>,
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and
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<inlineequation><mml:math>
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<!-- eqn: ascent+descent:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">ascent</mml:mi>
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<mml:mo>+</mml:mo>
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<mml:mi mathvariant="italic">descent</mml:mi>
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</mml:mrow>
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</mml:math></inlineequation>,
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respectively.
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<inlineequation><mml:math><mml:mi mathvariant="italic">xmove</mml:mi></mml:math></inlineequation>
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is taken from the glyph's
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<inlineequation><mml:math><mml:mi mathvariant="italic">width</mml:mi></mml:math></inlineequation>
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metric,
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and
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<inlineequation><mml:math><mml:mi mathvariant="italic">ymove</mml:mi></mml:math></inlineequation>
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is set to zero.
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Finally,
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the glyph's image is converted to the appropriate format for <citerefentry><refentrytitle>glBitmap</refentrytitle></citerefentry>.
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</para>
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<para>
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Using <function>glXUseXFont</function> may be more efficient than accessing the X font and generating
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the display lists explicitly,
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both because the display lists are created on the server without requiring
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a round trip of the glyph data,
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and because the server may choose to delay the creation of each
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bitmap until it is accessed.
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</para>
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<para>
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Empty display lists are created for all glyphs that are requested and
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are not defined in <parameter>font</parameter>.
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<function>glXUseXFont</function> is ignored if there is no current GLX context.
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</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para>
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<constant>BadFont</constant> is generated if <parameter>font</parameter> is not a valid font.
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</para>
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<para>
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<constant>GLXBadContextState</constant> is generated if the current GLX context is
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in display-list construction mode.
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</para>
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<para>
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<constant>GLXBadCurrentWindow</constant> is generated if the drawable associated
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with the current context of the calling thread is a window, and that
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window is no longer valid.
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>glBitmap</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glXMakeCurrent</refentrytitle></citerefentry>
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</para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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