How do I correctly pluralize acronyms? [duplicate]

Possible Duplicates:
What is the correct way to pluralize an acronym?
Plural form of the acronym LASER

I was just writing an email asking a supervisor about downloading multiple dynamic-link library files. The acronym for these is DLL, and the full spelling, dynamic-link library, is never used. How would this be pluralized, because normally I would just add an s, but DLLs is difficult to understand. Sometimes I add an apostrophe to make it DLL's, but I know this isn't grammatically correct. So my question is, how do I make the acronym DLL (and acronyms in general) plural?

Solution 1:

"DLLs" is fine. Just capitalize the acronym (it's actually an initialism which makes capitalization even more appropriate/necessary) but leave the plural letters lowercase.

Solution 2:

When I reffer to .dll files (or any file extension), I usually add "files" after to avoid confusion as to what a .dll is.

And I add a period before because .dll is a file type.

Just my own convention that works for me.