f1131623_sion_Reference__Special_Groups__Description
[Feature] Negative lookbehind [Syntax] (? [Example] (? [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] YES [Ruby] 1.9 [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] 
Matches at a position if the pattern inside the lookbehind cannot be matched ending at that position.
Regular Expression Reference: Special Groups