creo4 config.pro option documentation for: MFG_MILL_WINDOW_DEPTH_FIX 
close_corner_relief
Category: Sheetmetal
Description: Closes the gap between the bend surfaces of a corner that is a result of intersecting walls in the form state.
Values: yes, no
Default Values: no
_5_3_44_3" class="Body">This option ensures that the toolpath is accurately generated when you are using a mill window. The depth of a mill window is correctly assessed based on the reference normal direction.