Open jaw redemptions

I am unclear as to the current limits of what we are allowed to open-jaw as return awards from the UK. (Obviously this only really applies to [Chase] 241s, as otherwise they could be booked as two one-ways.)
e.g. East and West Coast USA?
USA and Canada or Mexico or Caribbean?
Peking and Japan or Singapore?
North and South Africa?
West and East Europe?

Unfortunately this is not as straightforward as publishing in a table I’m afraid. Open Jaws are permitted provided the surface sector is not longer than the flight sectors. This is driven by IATA ruling.