Caveat Tag Salad (Was: some ERB decisions)
At 11:01 AM 10/17/96 CDT, Michael Sperberg-McQueen wrote:
>The SGML ERB met Wed. Oct 16th and voted on
> B.11 Should XML forbid, allow, or require empty end-tags (7.5)?
The DPH and "graceful recovery" arguments seem to have carried the day.
Yet, I'd like to point out (at the risk of bothersome repetition) that the
*real life* experience of HTML suggests that we ignore the possibility of
tag salad at our peril.
Requiring GIs in end-tags is not enough. Leaving "graceful recovery" to
parser implementations is not enough. Not only should an unexpected endtag
be a "reportable error" (assuming we have an adequate definition of this),
but some normative statement (even if it's a non-binding "should") regarding
the forms of error recovery would be the better part of wisdom.
For instance: the error is not "unexpected endtag" but "endtag missing"
(implying "forced" closure of open subelements.)
Otherwise, given some fragment
<foo> blah <bar> yada </foo> mumble </bar>
it becomes easy for a parser implementor to give the user "what he wants":
overlapping elements. The lesson, historically proven: Tag Salad is **EASY**.
Simply assuming that it's "obvious" people will get their nesting right,
when explicit labelling of endtags makes the error particularly
*non*-obvious, is *very* unwise, IMHO.
"Features whose purpose is to cause errors should be removed" -- Erik Naggum