External file include

In data item values or label values, you can use a file reference rather than a literal value. You supply this in the format: [@fileName.ext]. Since you do not have scripting available right in the data stream, it is mightily convenient that something like [@$A/myAdImage.jpg] does work, first hardening the $A to whatever path it is defined to be. Similarly for [@$U/Clauses/myClause.rtf].

Please see also _file.resolveName as the scripting way to "harden a path".