diff --git a/man2/select.2 b/man2/select.2
index 8af03c38f..ee42ef259 100644
--- a/man2/select.2
+++ b/man2/select.2
@@ -163,7 +163,10 @@ this is useful after
 returns.
 .PP
 .I nfds
-is the highest-numbered file descriptor in any of the three sets, plus 1.
+should be set to the highest-numbered file descriptor in any
+of the three sets, plus 1.
+The indicated file descriptors in each set are checked, up to this limit
+(but see BUGS).
 .PP
 The
 .I timeout
@@ -328,6 +331,7 @@ becomes undefined.
 An invalid file descriptor was given in one of the sets.
 (Perhaps a file descriptor that was already closed,
 or one on which an error has occurred.)
+However, see BUGS.
 .TP
 .B EINTR
 A signal was caught; see
@@ -542,6 +546,18 @@ To monitor file descriptors greater than 1023, use
 .BR poll (2)
 instead.
 
+According to POSIX,
+.BR select ()
+should check all specified file descriptors in the three file descriptor sets,
+up to the limit
+.IR nfds\-1 .
+However, the current implementation ignores any file descriptor in
+these sets that is greater than the maximum file descriptor number
+that the process currently has open.
+According to POSIX, any such file descriptor that is specified in one
+of the sets should result in the error
+.BR EBADF .
+
 Glibc 2.0 provided a version of
 .BR pselect ()
 that did not take a