In Section 2 on notational conventions we say "The key words must, must not, required, shall, shall not, should, should not, recommended, may, may not and optional in this document are to be interpreted as described in [RFC2119]." Which is fine except for the words "required" and "optional" which we use in several different senses. Section 21 on optional features of the DFDL standard uses "optional" vs. "required" in this sense of RFC2119. But we also use "Optional Occurrence", "Optional Element" very specifically and define them in our glossary. (Along with Required Occurrence and Required Element.) So the above sentence on notational conventions we should just drop the words "optional" and "required". I looked for synonyms for required/optional. mandatory/nonmandatory and compulsory/noncompulsory are ones that we might consider using in the future. We do use mandatory now as in mandatory alignment of character set code units. Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | www.tresys.com Please note: Contributions to the DFDL Workgroup's email discussions are subject to the OGF Intellectual Property Policy <http://www.ogf.org/About/abt_policies.php>