entry is a reserved identifier in K&R1, which seems to come from PL/I and FORTRAN.
Someone already posted a question about entry here, and the accepted answer said some compilers implemented it, but the K&R2 states
entry, formerly reserved but never used, is no longer reserved
Who is right ? Did the K&R2 take a shortcut because it was almost not used, and maybe it wasn't relevant for the reader ? Then, if entry has existed, which compilers did implement it ?
In their answer, the author also shared this link, but it only suggests some compilers implemented it, without giving any example though :
Some C compilers prior to the standard implemented that keyword. Since it was never part of any version of the C standard, it has no defined standardized meaning.
I asked this question by curiosity, as I'm very interested about early C.