I think it is, yes. The introduction says: "This manual incorporates the former GNU C Preprocessor Manual, which was among the earliest GNU Manuals. It also us

I think it is, yes. The introduction says: "This manual incorporates the former GNU C Preprocessor Manual, which was among the earliest GNU Manuals. It also uses some text from the earlier GNU C Manual that was written by Trevis Rothwell and James Youngman."