[Doc-SIG] scope of the parser

[Alan Jaffray]

Since the rules for which references are associated with which targets
are defined by reStructuredText, shouldn't the parser explicitly state
which target is to be used for each reference?  Ditto for footnotes,
inline directive references, etc.  It seems misplaced for an output
formatter to be dealing with details of autonumbering, ambiguous
refnames, etc.

Meanwhile, since the meaning of directives and the set of meaningful 
directive names is *not* defined by reStructuredText, shouldn't the
rST parser output most directives (including unknown ones) untouched?
It seems advantageous to be able to decouple directive processing and
implementation from reStructuredText parsing and implementation.

Alan