Class precedence list:

ext:character-conversion-input-output-stream, ext:character-conversion-input-stream, ext:character-conversion-output-stream, ext:character-conversion-stream, ext:encapsulating-character-output-stream, ext:encapsulating-output-stream, ext:encapsulating-character-input-stream, ext:encapsulating-input-stream, ext:encapsulating-character-stream, ext:encapsulating-stream, ext:character-input-stream, ext:input-stream, ext:character-output-stream, ext:output-stream, ext:character-stream, stream, standard-object, ext:instance, t.

Character conversion input and output stream.