(Is there a significant difference between "dot" and "period"?
Internet
search is not really helping here.)
In my opinion (but I don't know how to validate it), "period"
unambiguously refers to the "." character while "dot" could mean any
dot-like character. Of course, I don't see any other dot-like
characters
on my keyboard, but there's always unicode.
On the other hand, I think of a period as a punctuation mark at the
end of
a sentence, and that's not how we're using it here. "dot" is more
general.
The phrase "period character" seems to be unambiguous and avoids
suggesting any semantics, so maybe that's best for formal
documentation.