I started building examples implementing the new discriminator semantics for each type of point of uncertainty . I only got as far as simple choices with simple and complex elements as there seem to be lots of different cases. It is worth sharing anyway to see if we are on the right track. The long form discriminator is very verbose do is it worth inventing a short form or will it always be done by tools anyway? Alan Powell MP 211, IBM UK Labs, Hursley, Winchester, SO21 2JN, England Notes Id: Alan Powell/UK/IBM email: alan_powell@uk.ibm.com Tel: +44 (0)1962 815073 Fax: +44 (0)1962 816898 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