In version 7.07.1584374000 20200316 and later, the escape \<nomatch\> may be given as an expression. This will match and return non-empty data that is not returned by any other (non-\<nomatch\>) expression. It may only be given if other such expressions are given as well in exprs, since it is a negation. This may be useful when parsing text with multiple complex expressions, as a catch-all to match remaining space etc. that "falls through".