From e55abf41404dfbb7941337ba4f22b05f03dd5eb6 Mon Sep 17 00:00:00 2001
From: Kevin Ryde <user42@zip.com.au>
Date: Thu, 3 Feb 2005 23:17:27 +0000
Subject: [PATCH] (File Ports): In port-filename, cannot use after close.

---
 doc/ref/api-io.texi | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/doc/ref/api-io.texi b/doc/ref/api-io.texi
index 4a38a8378..ac9bb3e77 100644
--- a/doc/ref/api-io.texi
+++ b/doc/ref/api-io.texi
@@ -812,6 +812,9 @@ used only during port creation are not retained.
 Return the filename associated with @var{port}.  This function returns
 the strings "standard input", "standard output" and "standard error"
 when called on the current input, output and error ports respectively.
+
+@var{port} must be open, @code{port-filename} cannot be used once the
+port is closed.
 @end deffn
 
 @deffn {Scheme Procedure} set-port-filename! port filename