[V8i] Pen Table Text Substitutions

Question

Hello all, 
 I'm trying to create a text substitution that will insert a range of characters from the file name. 
 
 For example, I have a dgn named 123_plan.dgn. 
 My border contains the text $DGNNUMBER$ 
 I have defined a text substitution in my pen table as follows: 
 Actual Replacement 
 $DGNNUMBER$ _FILES_ 
 
 The result, of course, is that if I print 123_plan.dgn with this pen table, I get "123_plan.dgn" in my border in place of "$DGNNUMBER$". 
 What I'd like to do, is modify the replacement to only part of the filename. What would I need to do in order for the replacement to show "123" instead of "123_plan.dgn"? 
 
 Thank you.

Dawn Clark Gentry · Accepted Answer

The following named expression will work using your example. It picks up the file name starting at character number 4 and grabs the next 6 characters. 
 System.String.SubString(System.Path.GetFileNameWithoutExtension (PrintDefinition.SourceFile), 4, 6)

Ed Yepes · Answer

Try the following for me to see the Symbol Sets 
 Open Print Organizer before you open Named Expressions