To me, inasmuch as use of the word functionality referring to software means the extent of its overall ability, I would write "The software implements the following functionality." However, I've seen (from my Indian counterparts), "The software implements the following functionalities." To me, this just sounds awkward and wrong. In fact, as I just typed functionalities, the text box editor underlines it in red. And yet, I read all over the internet that the plural of functionality is functionalities so I don't know why it should be flagged. However, I guess that's not my question. My question is as in the title; are both examples above correct inasmuch as the software quite obviously will implement more than one piece of functionality?
Edit
Based on the comments below, let me rephrase my titular question. Are both examples above correct English? If so, do they both convey the same message? The way I'm employing functionality only feels plural, but that wasn't the essence of my question.
Edit 2
It looks like someone edited my titular question which is good because the focus below became too much on pluralization vs. idiomatic correctness. It appears that both uses are idiomatically correct. However, within the "anglosphere", as Dan calls it, functionality is most commonly (and properly) used as a mass noun. From the Meriam Webster's Online Dictionary referenced below, functionality is defined as: "the particular use or set of uses for which something is designed".
Best Answer
Google defines functionality as the range of operations that can be run on a computer or other electronic system, so we would expect either "functions" or "functionality." The arguable exception would be if we were referring to multiple systems, each with a different functionality.