[Boost-users] [regex] - bk_parens and bk_braces missing from 1.33.x

Resending due to no response since 4th Feb: It states in history.html for regex 1.33.0 that "some of the more esoteric options have now been removed, so there is the possibility that existing code may fail to compile: however equivalent functionality should still be available". I suppose bk_parens and bk_braces could be considered esoteric, but I cannot find any equivalent functionality. Is that intentional? Thanks, Keith MacDonald