M4 motorway M4 motorway The M4, a motorway in the United Kingdom running from west London to southwest Wales, was originally referred to as the London-South Wales Motorway. The English section to the Severn Bridge was constructed between 1961 and 1971; the Welsh element was completed in 1993. The Second Severn Crossing officially renamed the Prince of Wales Bridge, was inaugurated on 5 June 1996 by HRH The Prince of Wales and the M4 was rerouted. Apart from its two spursthe A48(M) and the M48the M4 is the only motorway in Wales. From London to Bristol, the M4 runs close to the
M4 (computer language) FreeBSD, NetBSD, and OpenBSD provide independent implementations of the m4 language. Furthermore, the Heirloom Project Development Tools includes a free version of the m4 language, derived from OpenSolaris. "GNU m4" is an implementation of m4 for the GNU Project. It 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