I recall this being discussed before, but not what came of it: is there
a problem with just ignoring <?foo where foo is anything other than php
or =? <?foo or <?bar or <?whatever is a parse error anyway so I very
much doubt there's any BC break. Unless someone's program relies on
parse errors.
The problem there becomes legacy support for:
<?foo();?>
And before you say "just watch for parens" there's also:
<?foo::bar();?>
and a much more insiduous example:
<?die ?>
no semicolon, no parens, no paamayim nekudotayim, nothing but a perfectly valid looking PI tag.
-Sara