Elimination mechanism in alkenes Do E2 elimination reactions occur in alkenes? If not, what mechanism is used?

If they do, are they limited by any stereochemical rules as alkanes do (antiperiplanar)?

My question is pernitent to the alkyne reaction mechanism, where both the E and Z alkenes undergo elimination to form the alkyne.

My guess is E2 mechanism is possible for the Z alkene, while the E alkene undergoes E1
No E1elimination. E2 in both cases. The E-isomer has a good overlap; syn elimination. The Z-isomer goes through anti elimination.