Hi, I have attached a document that discusses the support of uncertainty within DFDL. It is an extension of the choices document that was discussed at the last F2F but now includes choices, element wildcards, optionality, substitution groups and late binding of DFDL Schemas. There is an Alternatives Considered section at the end which contains ideas that were considered but rejected. Regards, Geoff Judd Websphere MQ Integrator Development IBM United Kingdom Ltd. Hursley Telephone: +44-1962-818461 E-mail: JUDDG@uk.ibm.com