This is a link to a format description language (proprietary) which mentions a pointers/offsets capability. http://www.binarydom.com/sdk/doc/bddl.shtml We may want to review this w.r.t. DFDL capabilities being considered in this area. There aren't too many of these to draw from in standardization. I am trying to get the Tresys one (which is not part of Daffodil) into form where we can describe it here also. 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>