Release Notes: document ECN vs TOS issue clearer for 3.1

diff --git a/doc/release-notes/release-3.1.sgml b/doc/release-notes/release-3.1.sgml
index def62067bc0e917a4e40faa68db33b3b2065f35c..814c42a8565ad0733f1ed4684c008f62a4abd73b 100644 (file)
--- a/doc/release-notes/release-3.1.sgml
+++ b/doc/release-notes/release-3.1.sgml
@@ -899,9 +899,13 @@ logformat icap_squid %ts.%03tu %6icap::tr %>a %icap::to/%03icap::Hs %icap::<size
         RFC2475, and RFC3260.
 
         The TOS/DSCP byte must be exactly that - octet value 0x00-0xFF.
-        Note that in practice often only values up to 0x3F are usable
-        as the two highest bits have been redefined for use by ECN
-        (RFC3168).
+        Note that in practice often only multiples of 4 is usable as the
+        two rightmost bits have been redefined for use by ECN (RFC 3168
+        section 23.1).
+
+        Note that in practice often only values up to 0xFC are usable,
+        and only in multiple of 4, as the two rightmost bits have been
+        redefined for use by ECN (RFC3168).
 
         This setting is configured by setting the source TOS values: