I should have added that this is compatible with Perl.
Indeed. But it is a strange logic (in my point of view) that /(?=(*:x))(q|)/K keeps the MARK:x value while the /(?=(*:x))((*:y)q|)/K don't. Isn't it? --## List details at https://lists.exim.org/mailman/listinfo/pcre-dev
