Administration > Environment Variables > APTDITAPATH — Specifying the Path for DITA References
  
APTDITAPATH — Specifying the Path for DITA References
Specifies the default paths for the set ditapath option, which is the list of path names to directories used to locate content referenced from DITA documents. The DITA references path is used when a reference is not specified as either an absolute path name or a path name relative to the current document directory. The DITA references resolved by this variable include topic references, content references, links, cross references, and any other DITA element that references content. The only exception to this is graphic references, that are resolved using the set graphicspath option.
Separate each directory in the DITA references path by a semicolon. You can use symbolic parameters in the DITA references path. The default path is Arbortext-path\ditarefs.
The DITA references path can also be set in the File Locations category of the Tools > Preferences dialog box.
If you want to make files referenced by DITA automatically accessible, use the Arbortext-path\custom\ditarefs directory to load them automatically upon startup.