This directory contains source code for the GNU Project's C preprocessor. Unlike this preprocessor, the compilers bundled with some systems have arbitrary limits on the number of significant characters in identifiers which make them unable to compile GNU Emacs. The Emacs build process tries to detect when it is running on such a system; if it is, it builds this C preprocessor, and then uses it to edit the Emacs source code into a form that the system's compiler can handle.
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.