Generic XML Tag Closer </> (GXTC)

May I seek some opinions on this topic/proposal?

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To extend XML spec just a little to permit use of "</>" (GXTC)
to be placed wherever it is permitted in the current XML spec
to place a closing tag.  The semantics will be to effect a
closing of the nearest open tag before the position of GXTC.
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Any opinion is fine, useful, crazy, nonsense, should be done,
must not coz it's going to break many things ...

I could see some good use of it, but do note the deep potential
impact it may bring.  Would like to hear from you.

Thanks.

cheers,
mc