Ant script

An Ant script is an XML build file, containing a single project and a single or multiple targets, each of which consists of a group of tasks that you want Ant to perform. A task is an XML element that Ant can execute to produce a result. Ant comes with a large number of built-in tasks; you can also add tasks of your own.

DITA Open Toolkit makes use of two kinds of Ant scripts:
System scripts
System-level scripts handle DITA source file processing and transformation into published output. They are an integral part of DITA Open Toolkit and should never be modified by users. The files are located in the ditaot root directory.
User scripts
User-level processing scripts are created and modified by users. They provide to the system scripts (which do the actual processing) information about the names and locations of the DITA source files, where to put the processed target files, and values for specific processing parameters. DITA Open Toolkit contains a number of sample user-level processing files that you can view to gain understanding of the build process, and modify for your own use.
Related concepts
Apache Ant
Build file
Processing (building)
Ant processing parameter
DITA Toolkit processing log