8. Programming in M4

Autoconf is written on top of two layers: M4sugar, which provides convenient macros for pure M4 programming, and M4sh, which provides macros dedicated to shell script generation.

As of this version of Autoconf, these two layers are still experimental, and their interface might change in the future. As a matter of fact, anything that is not documented must not be used.

8.1 M4 Quotation		Protecting macros from unwanted expansion
8.2 Programming in M4sugar		Convenient pure M4 macros