Language spec syntax howto

Hi,

I'm trying to extend the R language spec but I'm having a hard time
undertsanding the syntax of the spec files. I'm not a programmer so
looking at the gtksourceview source does not help ... I'd like to know
if there are and howto or something that helps understanding this syntax.

One example, I want to add 2 new comment highligths "doubt" and "strong"
and I use the following code

  <line-comment _name="Comment strong" style="Comment">
    <start-regex>^(#!)</start-regex>
  </line-comment>
  <line-comment _name="Comment doubt" style="Comment">
    <start-regex>^(#\?)</start-regex>
  </line-comment>
  <line-comment _name="Line Comment" style="Comment">
    <start-regex>#</start-regex>
  </line-comment>


which work for "strong" but not for "doubt". Both are valid regex.

Regards

EJ