Basically you cant do leg, knee, spinal, neck, shoulder & wrist locks/cranks. You can also not apply a choke across the face or jaw or use pressure points to get a submission.
As for kimuras/americanas/keylocks whatever you wanna call them - it is often hard to tell where the pressure is being applied so generally they are accepted unless it is really obvious the target is the shoulder.
Note that in a competition it is often hard to judge where the submission was gained. For example, if they turtle & defend by tucking their chin into their chest, seasoned competitors will hunch over & hide their actions so that if the lapel or arm goes across the face (illegal) then the ref wont see.... & if the ref (including the corner judges) cannot see & the guy taps from a "jawbreaker" - then he cannot rule it was illegal & therefore the submission stands (even if the other person complains).
So just because a technique is illegal doesnt mean it is never used.