Karl Berry Olaf Bachmann and many others. Diversions Diversions are a facility in M4 for diverting text from the input stream into a holding buffer. There is a large number of diversion buffers in GNU M4, limited only by available memory.
Text is diverted and undiverted using the divert and undivert macros.
They expand to the empty string, with the side effect of setting the diversion. This goes at the beginning. This goes at the beginning. This goes at the end. It is unlikely that you will want to use diversions in your own macros, and it is difficult to do reliably without understanding the internals of Autoconf.