Without further ado, the following was found: Issue: I<egrep> → B<egrep>(1) "Regular expressions (\"RE\"s), as defined in POSIX.2, come in two forms: " "modern REs (roughly those of I<egrep>; POSIX.2 calls these \"extended\" " "REs) and obsolete REs (roughly those of B<ed>(1); POSIX.2 \"basic\" REs). " "Obsolete REs mostly exist for backward compatibility in some old programs; " "they will be discussed at the end. POSIX.2 leaves some aspects of RE syntax " "and semantics open; \"\\*(dg\" marks decisions on these aspects that may not " "be fully portable to other POSIX.2 implementations."
