The grep 3.8 man page at https://www.gnu.org/software/grep/manual/grep.html says, under "What happened to egrep and fgrep?":
egrep and fgrep were not standardized by POSIX This is factually incorrect. They were included in POSIX.2-1992 but marked as obsolescent. When POSIX.2-1992 and POSIX.1-1996 were merged (along with the Single UNIX Specification) to form POSIX.1-2001, the obsolescent features from POSIX.2-1992 were removed. Suggested fix - change: egrep and fgrep were not standardized by POSIX and are no longer needed to: egrep and fgrep were marked obsolescent when they were standardized by POSIX in 1992 and were removed in the 2001 revision; they have long been deprecated by GNU. (I have it second hand that the GNU deprecation occurred in 2007; you could give that date instead of saying "long" if you can confirm it.)
