AEC Modify - Subtract

I've been using the AEC Modify - Extend and Trim commands for extending and trimming to profile objects and its been working well. I thought I would take a look the subtract tool. This one would be a useful in creating details.

It takes linework and trims out one linework from another. The two benefits of this command is that you can trim blocks with it and trim with AEC objects, such as subassemblies. To use just right click in model or paper space and choose AEC Modify Tools> Subtract select the linework you are going to subtract from (or edit) then press enter and then choose the objects that are going to subtract from the first objects selected.

Look on page 1395 of the User's Guide for a picture of how the command works.

The User's Guide is located at C:\Program Files\Autodesk Civil 3D 2008\Help\civil_ug.pdf