Just a "stab in the dark" ... run the XClip command with its Generate Polyline feature, then run it again with Select Polyline, the Erase the polyline.
Obviously there might be cleaner code than doing everything through the command line, but hell, it's quick & simple!
Yeah, this is one option I have considered, but using this method I have to first determine if the Xref is clipped or not, there may be hundreds of xrefs to deal with and this is selecting all of them.
Ummm... have you tried minimize the number of xrefs in a drawing??
They are not my drawings, these are drawings we get from Architects and such, so unfortunately this is not a possible solution, although I wish it were. What I am doing is working on a routine that will change all Xrefs from Overlay->Attach or Attach->Overlay, I have a routine that does this, but it is slow and a bit buggy, so I am trying to remove as many of the bugs as I can.
Ok, that gets me a start, thank you, I will now need to figure out how I am going to apply that boundary, I guess the first step is to determine how many points, so I know if it is a polygonal clip or a rectangular clip.