&gt; Most RE engines that are described as being an NFA<p>Yes, and it&#x27;s a huge disservice to continue doing so. It doesn&#x27;t make any sense to describe Perl&#x27;s (or Java&#x27;s, or Python&#x27;s or PCRE) regex implementation as an NFA.<p>&gt; but everyone knows what you mean when you talk about them<p>I disagree. The confusion in this space is extremely high.