Add warning that on Windows it only works on sockets.

diff --git a/Doc/lib/libselect.tex b/Doc/lib/libselect.tex
index eec8de1ac24782ad5581ec94d05e2aef0b5a1d19..888914e4b8b333e10b1379c2115bca1869058509 100644 (file)
--- a/Doc/lib/libselect.tex
+++ b/Doc/lib/libselect.tex
@@ -6,7 +6,13 @@
 
 
 This module provides access to the function \cfunction{select()}
-available in most \UNIX{} versions.  It defines the following:
+available in most operating systems.  Note that on Windows, it only
+works for sockets; on other operating systems, it also works for other
+file types (in particular, on \UNIX{}, it works on pipes).  It cannot
+be used or regular files to determine whether a file has grown since
+it was last read.
+
+The module defines the following:
 
 \begin{excdesc}{error}
 The exception raised when an error occurs.  The accompanying value is