Changing language in CATIA V5

To change the intraface language in CATIA go to Tools > Customize..., go to tab Options and choose the User Interface Language.

Extrusion of a self intersecting/open profile

Normally CATIA does not allow user to extrude an open or self intersecting profile. It is not possible to extrude such profile unless you define a thickness of the extrusion.

Polygon UDF