To define excavation subspaces for conventional and TBM
tunnels, the user must access the Excavation Subspaces Catalog or Excavation
Subspaces Templates GUI.
In this GUI, all of the tunnel cross sections will be
listed. Using the Define option, the 2D Sketcher mode is opened and the user
can tag closed boundaries (similar to conventional lining parts) as excavation
subspaces.
