Fixed index module reference.
diff --git a/Doc/lib/libsun.tex b/Doc/lib/libsun.tex
index 909c14d..a579872 100644
--- a/Doc/lib/libsun.tex
+++ b/Doc/lib/libsun.tex
@@ -105,7 +105,9 @@
 symbolic constants like \code{MIN_GAIN}, \code{MAX_GAIN},
 \code{SPEAKER}, etc. The names of
 the constants are the same names as used in the C include file
-\file{<sun/audioio.h>}, with the leading string \samp{AUDIO_} stripped.
+\file{<sun/audioio.h>}, with the leading string \samp{AUDIO_}
+stripped.
+\refstmodindex{SUNAUDIODEV}
 
 Useability of the control device is limited at the moment, since there
 is no way to use the ``wait for something to happen'' feature the