[TxMt] language grammar suggestion: auto-numbering captures

[Timothy Bates]

It seems there is no way to have parts of a capture scoped by calls  
to $self or #repository elements, which means that complex captures  
get to have many capture elements.

It would be handy if there was a code for language grammar capture  
numbering, so that these are more resilient and self-healing when the  
regexp underlying their definition changes.

What I would suggest for TM2 is something like a code for "next  
group" so instead of explicitly numbering all matches, only non- 
sequential elements are explicitly numbered, and all others are self  
numbering. A nice code would be "#". A nice twist would be if this  
supported skipping elements when suffixed with an addition "#++" or "# 
+n"

Then, if we change a match from, say:
     match = '(a)(b)(c)';
To say:
     match = '(a)(a1)(b)(c)';

Then the numbering, instead of manually being recoded from this:
1 = { name = 'a'; };
2 = { name = 'b'; };
3 = { name = 'c'; };
to this:
1 = { name = 'a'; };
2 = { name = 'a1'; };
3 = { name = 'b'; };
4 = { name = 'c'; };

Could simply stay as this (where # is a code for "next sequential  
number"
1 = { name = 'a'; };
# = { name = 'a1'; };
# = { name = 'b'; };
# = { name = 'c'; };

In the more complex case,

1     = { name = 'a'; };
#     = { name = 'a1'; };
#+1 = { name = 'b'; }; //skips a group
#     = { name = 'c'; };