-A mood defines a subset of audio files called the *admissible audio files*
-for that mood. A mood can be *active* which means that para_server
-is going to select only files from that subset of admissible files.
+A mood defines a subset of audio files called the *admissible audio
+files* for that mood. At any time, at most one mood can be *active*
+which means that para_server is going to select only files from that
+subset of admissible files.