GNU m4 is an implementation of the m4 macro preprocessor. Developed by the GNU Project, GNU m4 is designed to avoid many kinds of arbitrary limits found in traditional m4 implementations, such as maximum line lengths, maximum size of a macro and number of macros. Removing such arbitrary limits is one of the stated goals of the GNU Project.The GNU Autoconf package makes extensive use of the features of GNU m4.GNU m4 is currently maintained by Gary V. Vaughan and Eric Blake.