This feature allows authors to show parts of code. It also lets allows the author to insert comments within the code using callouts.
This was used to demonstrate how a catalogue file is configured (see Section 4.3). That code is shown below. If the callout feature is not needed, it is possible to eliminate the areas between <areaspec> and <calloutlist>.
<example id="sample-catalog"> <title>Catalog Sample</title> <programlistingco> <areaspec> <area coords="1" id="ex.catalogue.comment"> <area coords="5" id="ex.catalogue.definition"> <area coords="11" id="ex.catalogue.eof"> </areaspec> <programlisting> -- Catalogues for the Conectiva S.A. Style -- OVERRIDE YES PUBLIC "-//Conectiva SA//DTD books V1.0//EN" "/home/ldp/estilos/livros.dtd" DELEGATE "-//OASIS" "/home/ldp/SGML/dtds/catalog.dtd" DOCTYPE BOOK /home/ldp/SGML/dtds/docbook/db31/docbook.dtd -- EOF -- </programlisting> <calloutlist> <callout arearefs="ex.catalogue.comment"> <to> Comment. Comments begin with <quote>--</quote> and follows to the end of the line. </to> </callout> <callout arearefs="ex.catalogue.definition"> <to> The public type association <parameter class="option">"-//Conectiva SA//DTD books V1.0//EN"</parameter> with the file <filename>books.dtd</filename> on the directory <filename class="directory">/home/ldp/estilos</filename>. </para> </callout> <callout arearefs="ex.catalogue.eof"> <para> Comment informing the end of the file. </para> </callout> </calloutlist> </programlistingco> </example> |
The listings can be directly inserted in the document's body without the need of the <example> or <para> elements.
The calling coordinates' specifications are done with reference to the code line which will be commented upon.