Such a data can be found in instruction sheet, as in attachment for instance.

The values expressed as Mxx (e.g. M6,M10, M12) means there is a hole in busbar for connecting the cable with cable lug.
So max cable cross-section then depends on the cable lug you buy.
If you buy cable lug e.g. Cu120 - 12 (see picture) it means that this lug is dedicated for 120mm2 cable and has hole prepared for mounting using M12 bolt.

Released for: Schneider Electric Egypt and North East Africa