Whether to add a zero-length string or hexBinary to the infoset for an optional element depends on the setting of emptyValueDelimiterPolicy. A setting of 'none' stops it from being added. Regardless, it does not give a processing error, so is therefore known-to-exist, and therefore does not cause backtracking, so preserving discriminators and variables. Regards Steve Hanson IBM Hybrid Integration, Hursley, UK Architect, IBM DFDL Co-Chair, OGF DFDL Working Group smh@uk.ibm.com tel:+44-1962-815848 mob:+44-7717-378890 Note: I work Tuesday to Friday From: Mike Beckerle <mbeckerle.dfdl@gmail.com> To: dfdl-wg@ogf.org Date: 24/07/2018 15:15 Subject: [DFDL-WG] clarification: on suppressed ZL string/hexBinary - do we keep variable assignments? Sent by: "dfdl-wg" <dfdl-wg-bounces@ogf.org> In some situations we parse and get a successful zero-length parse for a string or hexBinary. But because the occurrence is optional, we do NOT add an element to the infoset. In that case, what happens to side-effects that occurred during the successful parse. There are two possible kinds of side-effects. Variables can be set, and a discriminator can be set to true. It seems to me that if a discriminator is set, then that *must* be preserved, and in that case it would seem the variable settings should be retained as well. Comments? 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 -- dfdl-wg mailing list dfdl-wg@ogf.org https://www.ogf.org/mailman/listinfo/dfdl-wg Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU