Each SOUND entry is broken down into the following parts:
.PS "sound file"
.PL MESG
-message window mapping (the only one supported in 3.5);
+message window mapping (the only one supported in 3.6);
.PL pattern
the pattern to match;
.PL "sound file"
%.sd
%.si
-{\tt MESG } --- message window mapping (the only one supported in 3.5);\\
+{\tt MESG } --- message window mapping (the only one supported in 3.6);\\
{\tt pattern } --- the pattern to match;\\
{\tt sound file} --- the sound file to play;\\
{\tt volume } --- the volume to be set while playing the sound file.