f1131623_sion_Reference__Special_Groups__Description
[Feature] Atomic group [Syntax] (?>regex) [Example] a(?>bc|b)c matches abcc but not abc [JGsoft] YES [.NET] YES [Java] YES [Perl] YES [PCRE] YES [PCRE2] YES [PHP] YES [Delphi] YES [R] YES [JavaScript] no [VBScript] no [XRegExp] no [Python] no [Ruby] YES [std::regex] no [Tcl ARE] no [POSIX BRE] no [POSIX ERE] no [GNU BRE] no [GNU ERE] no [Oracle] no [XML] no [XPath] no [Description] 
Atomic groups prevent the regex engine from backtracking back into the group after a match has been found for the group. If the remainder of the regex fails, the engine may backtrack over the group if a quantifier or alternation makes it optional. But it will not backtrack into the group to try other permutations of the group.
Regular Expression Reference: Special Groups