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<reference id="preprocess-debugfilter" xml:lang="en-us">
<title>Debug and filter (debug-filter)</title>
<shortdesc>The <codeph>debug-filter</codeph> stage processes all referenced
DITA content, and creates copies in a temporary directory for use
during the remainder of the build. Several modifications are made
during this process.</shortdesc>
<refbody>
<section>     <p>As the files are copied, the following modifications
are made:</p><ul>
<li>The files are filtered according to entries in any specified DITAVAL
file.</li>
<li>Debug information is inserted into each element (using the <codeph>xtrf</codeph> and <codeph>xtrc</codeph> attributes).
These values allow messages later in the build to reliably indicate
the original source of the error — for example, a message may trace
back to the fifth <codeph>&lt;ph></codeph> element in a specific source
document. Without these attributes, that count may no longer be available
due to filtering and other processing.</li>
<li>Adjust column names in tables to use a common naming scheme. This
is done only to simplify later conref processing; for example, if
a table row is pulled into another table, this ensures that a reference
to "column 5 properties" will continue to work in the fifth column
of the new table.</li>
</ul><p>This step is implemented in Java. </p></section>
</refbody>
</reference>
