As mentioned by others,  .*+ et al are syntactic sugar for  (?>...) 'atomic' grouping. See the extensive discussion of the latter under  (?>pattern) in the Extended Patterns section of perlre.

Update: See also Using independent subexpressions to prevent backtracking in the Part 2: Power tools section of perlretut.

In reply to Re: When would I want to use possessive quantifiers? by AnomalousMonk
in thread When would I want to use possessive quantifiers? by petdance

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