The "multiplicity automaton (MA)" is a model in compute science and its plural is "multiplicity automata". Should the plural of the abbreviation be MA or MAs?
What is the correct way to pluralize an acronym? is not a duplicate as it is focused on cases like "ATMs" where the expanded form "automated teller machines" has a regular plural ending in "s." Unlike "machines," the word "automata" has an irregular plural that does not end in "s." It's unclear from the linked answers how abbreviations that end in words like this should be pluralized. A high-ranking answer by Neil Fein mentions "VIPs," but a high-ranking comment by oosterwal says
VIPs' is a strange one. It could be argued that the expanded acronym, when pluralized, should be 'Very Important People' rather than 'Very Important Persons'. Using this argument, 'VIP' could be used as a singular or plural noun. "The VIP has arrived." "The VIP have arrived." I'm not sure anyone else would agree with my logic, though.