> Let me just note that the second version using :: is NOT ambiguous for
> the parser - the one using "." seems to be unless I am missing something
> obvious.

You have to treat ". with an alphabetic lookahead" as a different kind 
of token (that would be "."/[A-Za-z] in Flex).  Then there is no 
ambiguity anymore.

>> What I am a bit concerned about is that I've made the BNF grammar more
>> complex or that I've made it stupid. If a dot/period is followed by
>> whitespace, it terminates the current statement; else it can validly be part
>> of a word or keyword.

The BNF is not more complex if you move the distinction up to the 
lexical analyzer.

Paolo