I am new to Magento. I have an Community Edition 2.1.2 project running on my Linux box so I can learn the UI widgets.
So maybe this is a well-known in joke and I am just too new to get it.
PCRE usually refers to "Perl-compatible regular expressions". However, the M2 documentation (many places) translates PCRE as "regular exceptions". Exceptions?
I suspect this is a mistake.
Otherwise, the M2 documentation is understandable on technical details, though verbose, redundant and overly linked.
I have proposed the change on GitHub. This one page only. There are other pages needing this modification.