Macro
defsystem system-name options &key members rules
A symbol used as the name of the system. If a string is given, it is interned in the current package.
Any of a number of options that can be specified.
The members of the system. These may be files of Common Lisp source code, foreign source code, or other systems.
A set of rules describing the requirements for and order in which compilation and loading of the system members should take place.