What is the correct way to pluralize an acronym?
Let's say we're talking about PLCs (programmable logic controllers)? Or are they "PLC's"? I've seen it both ways!
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Either way is acceptable - it's a style issue. And by the way, your example isn't an acronym, it's an initialism or abbreviation. Acronyms are read out as words, like NASA, but not PLC or CIA.