2.4 How derived variables are named

Sometimes a Makefile variable name is derived from some text the maintainer supplies. For instance, a program name listed in `_PROGRAMS' is rewritten into the name of a `_SOURCES' variable. In cases like this, Automake canonicalizes the text, so that program names and the like do not have to follow Makefile macro naming rules. All characters in the name except for letters, numbers, the strudel (@), and the underscore are turned into underscores when making macro references.

For example, if your program is named sniff-glue, the derived variable name would be sniff_glue_SOURCES, not sniff-glue_SOURCES. Similarly the sources for a library named libmumble++.a should be listed in the libmumble___a_SOURCES variable.

The strudel is an addition, to make the use of Autoconf substitutions in macro names less obfuscating.