While Automake is intended to be used by maintainers of GNU packages, it does make some effort to accommodate those who wish to use it, but do not want to use all the GNU conventions.
To this end, Automake supports three levels of strictness—the strictness indicating how stringently Automake should check standards conformance.
The valid strictness levels are:
See Gnits, for more information on the precise implications of the strictness level.
Automake also has a special (and today deprecated) “cygnus” mode that is similar to strictness but handled differently. This mode is useful for packages that are put into a “Cygnus” style tree (e.g., older versions of the GCC and gdb trees). See Cygnus, for more information on this mode. Please note that this mode is deprecated and will be removed in the next major Automake release (1.13); you must avoid its use in new packages, and should stop using it in existing packages as well.