ANSI Common Lisp 1 Introduction 1.5 Conformance 1.5.1 Conforming Implementations
220.127.116.11 Documentation of Implementation-Dependent Features
A conforming implementation shall be accompanied by a document
that provides a definition of all implementation-defined
aspects of the language defined by this specification.
In addition, a conforming implementation is encouraged (but not required)
to document items in this standard that are identified as
implementation-dependent, although in some cases
such documentation might simply identify the item as "undefined."