[V8i] Pen Table Text Substitution in ProjectWise

I am trying $FILES$ to generate the file name with extension. I found that with the same pen table there might be two different outcomes between ProjectWise and Local drive. 

When the DGN uploaded to ProjectWise server, the Document Name will be the "file name + .DGN", and the Document Description will be "file name". So,

how to set the pen table text substitution that point to ProjectWise's Document Name but NOT the Document's Description?

Environment: MS V8i SS3, ProjectWise Explorer V8i