trim between lines(gap both side).
 
  File name : TRIMB2.LSP

This program is similer to TRIMB.LSP. 
This program makes gaps on end of trimed line.
You can use this program on herizontal stiffener. etc.
 

 
 Example
select first entity: {p1}               [Select lines that is not trimed (Example: vertical stiffener of steel box )]
select first entity: {p2}       
Ofset distance<0.0>: 30                [Enter Gap (30mm)]
Pick first point: {p1}          [Pick first point to select un trimed line (Ex:Horizontal stiffener)]
Pick second point: {p2}         [Pick secont point. ]
Pick first point: {p3}          [You can next plate]
Pick second point: {p4}
Pick second point:             [Type enter to finish this command]