GeezerVison

PHP 8.6 adds the form feed character to the default $characters set of trim, ltrim, and rtrim, so calls relying on the default would change behavior there. This passes an explicit character set at the five calls that relied on it: the notEmpty validation, comment and whitespace line detection, the name/value split (converted from a callable-string array_map('trim', ...) to a closure so it can carry the set), and blank-value detection all freeze the pre-8.6 set, keeping behavior identical on every PHP version.

The ltrim after the export prefix instead uses the full whitespace set, space, horizontal tab, line feed, carriage return, vertical tab, and form feed, matching the ctype_space guard on the preceding line. That guard already accepts form feed as the separator, but the pre-8.6 default never stripped it, so export followed by a form feed produced an invalid-name error; the two now agree on every PHP version. An audit of the rest of the package found nothing else: all other regex work goes through the Util\Regex result wrapper with PCRE error reporting, and every pattern is anchored with \A/\z or the A modifier.