Referencing files from other plug-ins

Starting with DITA-OT 1.5.4, you can use the plugin:*plugin-id* URI extension and the ${dita.plugin.*plugin-id*.dir} Ant variable to reference the base path of another installed DITA-OT plug-in.

Sometimes you need to reference content in another DITA-OT plug-in. However, the path to an installed plug-in is not guaranteed to be the same between different installed instances of DITA-OT. The plugin:*plugin-id* URI extension and ${dita.plugin.*plugin-id*.dir} Ant variable are provided so your build and XSLT files always use the correct path to the plug-in.

Within a single plug-in, you can safely use relative path references, for example, xsl/my.xsl without specifying the path to the plug-in itself.

Use ${dita.plugin.*plugin-id*.dir} in Ant build files.

Use the Ant variable ${dita.plugin.*plugin-id*.dir} anywhere in your build file or template to point to the base path of an installed DITA-OT plug-in.

The following example copies CSS files from the HTML5 plug-in:
```
<copy todir="${dita.temp.dir}/css">
  <fileset dir="${dita.plugin.org.dita.html5.dir}/css" 
           includes="*.css"/>
</copy>
```
Use plugin:*plugin-id* in XSLT files.

Use the URI extension plugin:*plugin-id* at the beginning of a file reference—usually in <xsl:import>—to point to the base path of an installed DITA-OT plug-in.

The following example imports the base output-message.xsl processing:
```
<xsl:import href="plugin:org.dita.base:xsl/common/output-message.xsl"/>
```
To use the URI extension, your plug-in must reference the DITA-OT catalog file. In your Ant build file, add an <xmlcatalog> element referencing the DITA-OT catalog file as a child of the <xslt> element.
```
<xslt style="xsl/my.xsl"
      in="${dita.temp.dir}/input.file" 
      out="${dita.temp.dir}/output.file">
  <xmlcatalog refid="dita.catalog"/>
</xslt>
```

For both of these methods, make sure you use the plug-in ID (defined in the plugin.xml file) rather than the folder name of the plug-in. In many cases, the folder name is not the same as the plug-in ID.

Related information

Plug-in coding conventions

DITA-OT mdBook Demo

Referencing files from other plug-ins