Both, actually. Enhancement is part of the original NESMA functional sizing standard (section 3.6.3). The description there is somewhat concise. An additional guideline document exists, as well. It gives more detail on how to count what cases, but it is NOT part of the standard: The resulting function points of the second guideline (“EFP”) are not equivalent to the function points of the original sizing standard (“PFP” – “Project Function Points”).
NESMA is aware that sizers need more guiding when counting enhancement using the standard (“PFP”). On the old NESMA site, there have been minutes and forum posts which explained that this is known and gave some initial guidance, but they are all gone now. If anyone from NESMA can point me to the current state of affairs, it would be greatly appreciated.
P.S.: I’ve just noticed that it’s you, Frank. Certainly, you must know all of what I’ve written already? Were you hoping for an “official” reaction?