Re: Adding missing copyright years

[Richard Stallman]

    This can't be done completely mechanically, since one has to check
    when the last copyrightable changes (and not all changes are
    copyrightable) have been, correct?

That's correct, aside from one subtle point.  It's not that "not all
changes are copyrightable" but rather that "not all changes are big
enough to count for copyright purposes".  So the question, for each
year, is "were substantial changes made during that year".  If yes,
that year should be mentioned.

Substantial means adding up to more than 10-15 lines of total change.

So yes, a human being has to check it.