Mold Design and Casting > Working with Volumes > Gathering Volumes > Selecting Surfaces
  
Selecting Surfaces
If the gather references for a mold volume have been selected already, and Select is chosen from the GATHER STEPS menu a second time, the GATHER SPEC menu, with the commands Type and References, appears, rather than the GATHER SEL menu. You can then reselect the type—Surf &Bnd or Surface—and the reference surfaces.