are regular Lisp files that are executed by
Consequently, you can put whatever Lisp code you like into these files.
However, it is recommended to keep such forms to a minimal,
and to instead define
that you use with
If however, you might insist on including code in the .asd file itself,
e.g., to examine and adjust the compile-time environment,
possibly adding appropriate features to
If so, here are some conventions we recommend you follow,
so that users can control certain details of execution
of the Lisp in .asd files:
*standard-output*, so that users can easily control the disposition of output from ASDF operations.