Custom parameters allow you to pass job-specific options to the Ant task used by the DITA Open Toolkit during composition.
Here is the syntax for custom parameters used by the Ant task for composition jobs.
-Dname=value
For example:
-Dargs.draft=yes -Dargs.debug=no
The method used to supply custom parameters determines the precedence of the parameters. Custom Parameter settings are higher priority than composition profiles which are higher priority than environment variables.