HACKING: Offer advice, resource for POSIX Issue 4.

1 files changed, 7 insertions, 1 deletions

diff --git a/HACKING b/HACKING
index 318f9f8fb..9084c86b5 100644
--- a/HACKING
+++ b/HACKING
@@ -1,4 +1,4 @@
-    Copyright 2022 Free Software Foundation, Inc.
+    Copyright 2022-2023 Free Software Foundation, Inc.
 
     Copying and distribution of this file, with or without
     modification, are permitted in any medium without royalty provided
@@ -77,6 +77,12 @@ Writing Tests
 
 Here are some portability notes on writing automated tests.
 
+* Write to the POSIX standard for the shell and utilities where
+  possible.  Issue 4 from 1994 is old enough that no contemporary system
+  has a good reason for not conforming.  A copy of the standard is
+  available at the Open Group's web site.
+    https://pubs.opengroup.org/onlinepubs/009656399/toc.pdf
+
 * The "od" command on macOS can put extra space characters (i.e., spaces
   that don't correspond to the input) at the ends of lines when using
   the "od -t c" format; GNU od does not.