🚀 go-pugleaf

This may be very basic question but I really did
try to find the answer independently and I'm stumped.

How can I define a paired tag (one with a required
end_tag) that can be inserted at several places within
the tag heirarchy. 

That is assuming the heirarchy 

<a>
  <a1>
	<b1>
      blah blah blah
	<\b1>
  <\a1>
  
  <a2>
  <\a2>

<\a>

I wish to define a bracketing structure that could be inserted
around any of:
1) blah
2) <b1><\b1>
3) <a1><\a1>
4) <a><\a>

The catch is the legal list of contained elements needs to be 
inherited from the context in which the bracketing tag itself
was inserted (e.g. <bracket> under a1 may contain <bn> but under
<b2> it may only contain whatever is legal for <b2> )

For example consider the tag <LANGUAGE language="CHINESE"> </LANGUAGE>.
I wish to be able to place this tag around any arbitrary "chunk"
of data.

+(Language) for the <doc> tag won't get me there because any tags
found in <Language> would be illegal.

Are my only alternatives:
1) A bunch of +() -() sets for each bracketing tag
2) Define LANG1 LANG2 LANG3 for different locations in the Heirarchy.

Any help will be much appreciated.

Post here or ruben@dsp35001.boeing.com     Thanx...