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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="processing-structure">

<title>Processing structure</title>

<shortdesc>DITA-OT implements a multi-stage, map-driven architecture to process DITA content. Each stage in the

process examines some or all of the content; some stages result in temporary files that are used by later steps,

while others stages result in updated copies of the DITA content. Most of the processing takes place in a temporary

working directory; the source files themselves are never modified.</shortdesc>

<prolog>

<metadata>

<keywords>

<indexterm>architecture</indexterm>

<indexterm>pre-processing</indexterm>

<indexterm>Eclipse Help</indexterm>

<indexterm>HTML Help</indexterm>

<indexterm>XHTML</indexterm>

<indexterm>PDF</indexterm>

<indexterm>HTML5

<indexterm>pre-processing</indexterm></indexterm>

<indexterm>pipelines

<indexterm>description of</indexterm></indexterm>

<indexterm>pipelines

<index-see-also>pre-processing</index-see-also></indexterm>

</keywords>

</metadata>

</prolog>

<conbody>

<p>DITA-OT is designed as a pipeline. Most of the pipeline is common to all output formats; it is known as the

<term>pre-processing stage</term>. In general, any DITA process begins with this common set of pre-processing

routines.</p>

<p>Once the pre-processing is completed, the pipeline diverges based on the requested output format. Some processing

is still common to multiple output formats; for example, Eclipse Help and HTML Help both use the same routines to

generate XHTML topics, after which the two pipelines branch to create different sets of navigation files.</p>

<p>The following image illustrates how the pipeline works for several common output formats: PDF, Eclipse Help, HTML

Help, XHTML, and HTML5.</p>

<note>Other output formats may implement additional processing steps.</note>

<fig>

<title>Diagram of some possible paths through the transformation pipeline</title>

<image href="images/processing-flow.svg" placement="break" width="6.5in"/>

</fig>

</conbody>

</concept>