[gedit-list] Meaning of match-empty-string-at-*?

["Johan Tibell" <johan tibell gmail com>]

What exactly is the meaning of the match-empty-string-at-beginning/end
in the keyword-list element of gtksourceview .lang files? I'm trying
to match words on the form $identfier, this works but I'm unsure of
why:

<keyword-list _name = "Builtins" style = "Others" case-sensitive="TRUE"
       beginning-regex="\$"
       match-empty-string-at-beginning="FALSE"
       match-empty-string-at-end="TRUE">
       <keyword>array</keyword>
       <keyword>amake</keyword>
       <keyword>acopy</keyword>
       <keyword>asize</keyword>
       <keyword>asub</keyword>
       <keyword>ablit</keyword>
</keyword-list>

Does match-empty-string-at-beginning="FALSE" means that there should
be no spaces/tabs between the beginning-regex and the keyword? Is
there such a thing as end-regex? Otherwise, what function does
match-empty-string-at-end have and what's the correct value for it in
this case? Both true and false appear to work.

Is there a more efficient way to achieve the match I want?

Also is there a way to indicate what part of a regex match I want
highlighted. For example I would like type names (int, string, void,
etc.) to be highlighted if and only if the appear after a colon (:)
but I don't want the colon to be highlighted.