On Thu, Jul 5, 2012 at 12:44 AM, Rogers, Michael K <mroge02@emory.edu>wrote:

> On Jul 4, 2012, at 1:29 PM, Peter Münster wrote:
> > On Wed, Jul 04 2012, Hans Hagen wrote:
> >
> >> no, mixing this way is asking for troubles, if not now, than maybe in
> the
> >> future
> >>
> >> just use \section
> >
> > Yes, but isn't \startsection the recommended method for the future and
> > needed for XML output?
>
> XML documents should form a tree, so a structure like
>
> \startA % <A>
> \startB % <B>
> \stopA % </A>
> \stopB % </B>
>
> won't translate to XML.
>
> Grouping in TeX follows the same restrictions, and \start... and \stop...
> behave like \begingroup and \endgroup.  The \stop... is supposed to restore
> the state before the corresponding \start... (at least I assume so --
> \endgroup works that way).  One cannot stop A in the middle of B and return
> to the state before \startA without also stopping B.  So one should put
> \stopB before \stopA, not after it.
>
> It depends.

\starttext
\long\def\startA#1\stopA{<\low{A}#1>\low{A}}
\long\def\startB#1\stopB{<\low{B}#1>\low{B}}

\startA
textAA
\startB
textAB
\stopA
textBB
\stopB
\stoptext


is ok  (not the context way, btw: real code is more complex).


The meaning of this can be
content of \startA..\stopA = textAA ⋃ textAB
content of \startB..\stopB = textAB ⋃ textBB
\startA..\stopA ⋂  \startB..\stopB = textAB

If we are describing programs, textAB can be the common code between the
function A and B.



-- 
luigi