Using part of $PRPSHEET:"SW-File Name"

Morning all,

I need to be able to use part of:

\$PRPSHEET:"SW-File Name"

Out filenames consist of all number ID's... Project, Task, Revision, etc. however end with a description. How do I just show link this variable to the first 21 characters only? Is this possible?!

Thanks for your help,

David

SolidworksDrawings And Detailing