An editor variable can be created and included in any user-defined expression where a built-in editor variable is also allowed. For example, a custom editor variable may be necessary for configuring the command line of an external tool, the working directory of a custom validator, the command line of a custom XSLT engine, or a custom FO processor.
You can create or configure custom editor variables in the Custom Editor Variables preferences page. To create a custom editor variable, click the New button and specify the name that will be used in user-defined expressions, the value that will replace the variable name at runtime, and a textual description of that variable.