BUGS Many of these regular expressions are liable to tickle a serious bug in perl's regexp engine. The bug is that the * and + repeat operators don't always match an unlimited number of repeats: in some cases they are limited to 32767 iterations. Whether this bogus limit applies depends on the complexity of the expression being repeated, whether the string being examined is internally encoded in UTF-8, and the version of perl. In some cases, but not all, a false match failure is preceded by a warning "Complex regular subexpression recursion limit (32766) exceeded". This bug is present, in various forms, in all perl versions up to at least 5.8.9 and 5.10.0. Pre-5.10 perls may also overflow their stack space, in similar circumstances, if a resource limit is imposed. There is no known feasible workaround for this perl bug. The regular expressions supplied by this module will therefore, unavoidably, fail to accept some lengthy valid inputs. Where this occurs, though, it is likely that other regular expressions being applied to the same or related input will also suffer the same problem. It is pervasive. Do not rely on this module (or perl) to process long inputs on affected perl versions.