You can find any tool by the Menu Structure HERE: https://turbocaddoc.atlassian.net/wiki/display/TC21UG/Menu+Structure
You can find the menu location of any tool by name HERE: https://turbocaddoc.atlassian.net/wiki/display/TC21UG/Tools+Mapped+to+Menus
Center of Extents Snap
SEKE: E
 
Snaps to the center of extents of a 2D or 3D object. This is the center of the bounding rectangle (2D) or box (3D) that encloses the selected object.
