# Overriding an XSLT-processing step

You can override specific XSLT-processing steps in both the pre-processing pipeline and certain DITA-OT transformations.

## Procedure

1. Develop an XSL file that contains the XSL override.
2. Construct a plugin.xml file that contains the following content:

       <?xml version="1.0" encoding="UTF-8"?>
       <plugin id="plugin-id">
         <feature extension="extension-point" file="relative-path"/>
       </plugin>

   where:
   - plugin-id is the plug-in identifier, for example, com.example.brandheader.
   - extension-point is the DITA-OT extension point, for example,`dita.xsl.xhtml`. This indicates the DITA-OT processing step that the XSL override applies to.
   - relative-path is the relative path and name of the XSLT file, for example, xsl/header.xsl.
3. Use the dita install subcommand to install the plug-in.
   Note:
   For more information, see Installing plug-ins.

## Results

The plug-in installer adds an XSL import statement to the default DITA-OT code, so that the XSL override becomes part of the normal build.

## Example: Overriding XHTML header processing

The following two files represent a complete, simple style plug-in.

The plugin.xml file declares an XSLT file that extends XHTML processing:

    <?xml version="1.0" encoding="UTF-8"?>
    <plugin id="com.example.brandheader">
      <feature extension="dita.xsl.xhtml" file="xsl/header.xsl"/>
    </plugin>

The xsl/header.xsl XSLT file referenced in plugin.xml overrides the default header processing to add a banner:

    <?xml version="1.0" encoding="UTF-8"?>
    <xsl:stylesheet version="1.0"
                    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
      <xsl:template name="gen-user-header">
        <div><img src="http://www.example.com/company_banner.jpg"
                  alt="Example Company Banner"/></div>
      </xsl:template>
    </xsl:stylesheet>