CLIM defines an extension to the stream protocol that supports output recording. The stream has an associated output history record and provides controls to enable and disable output recording.
output-recording-stream [Protocol Class]
Summary: The protocol class that indicates that a stream is an output recording stream. If you want to create a new class that behaves like an output recording stream, it should be a subclass of output-recording-stream. Subclasses of output-recording-stream must obey the output recording stream protocol.
Summary: Returns t if object is an output recording stream; otherwise, it returns nil .
Summary: The class used by CLIM to implement output record streams. This is a subclass of output-recording-stream . Members of this class are mutable.
Common Lisp Interface Manager 2.0 User's Guide - 3 Mar 2015