Rolf I realize there are regex resources. But just citing them all doesn't mean any, or all describe "ee", for example:

    Metacharacters

Modifiers

    Overview
    Details on some modifiers
        /x and /xx
        Character set modifiers
        /l
        /u
        /d
        /a (and /aa)
        Which character set modifier is in effect?
        Character set modifier behavior prior to Perl 5.14
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Not knowing that "ee" even exists , and it not being in this doc's modifier list, well, is less than useful? I agree if I studied maybe 12 regex guides I might eventually get to "ee" but that would be like Christmas by then. I tossed my Camel book having read it cover to cover in the 2000s but I don't recall ee in there either.. But it was a long time ago..

Suggesting a bot that answers every question on every Perl forum with "read the docs"? But some questions are so obscure (like this) that if answered at all, its buried. I've successfully programmed in Perl since 1995 never knowing about or needing "ee" for example..

Sometimes YOU are a much better resource than a mountain of docs.