Add caveat on partial dependence on the "cl" module, only available on

IRIX systems.

Doc/lib/libaifc.tex

@@ -13,6 +13,10 @@ format that includes the ability to compress the audio data.
 \index{AIFF}
 \index{AIFF-C}
 
+\strong{Caveat:}  Some operations may only work under IRIX; these will
+raise \exception{ImportError} when attempting to import the
+\module{cl} module, which is only available on IRIX.
+
 Audio files have a number of parameters that describe the audio data.
 The sampling rate or frame rate is the number of times per second the
 sound is sampled.  The number of channels indicate if the audio is