For discussion at next WG call. Regards Steve Hanson Architect, IBM Data Format Description Language (DFDL) Co-Chair, OGF DFDL Working Group IBM SWG, Hursley, UK smh@uk.ibm.com tel:+44-1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 23/08/2013 16:20 ----- From: Alex Wood1/UK/IBM To: Steve Hanson/UK/IBM@IBMGB, Mark Frost/UK/IBM@IBMGB, dfdl-wg@ogf.org, Date: 23/08/2013 14:58 Subject: dfdl:lengthKind='prefixed' , different encodings for prefix and content where prefixIncludesPrefixLength is ‘yes. Hi All, Considering a case similar to that excluded by errata 2.76. An element with lengthKind 'prefixed' and prefixIncludesPrefixLength 'true' but where the prefix type and the element both have lengthUnits 'characters' but have different encodings (or specifically encodings with different lengths of characters). I believe the issue that 2.76 is trying to avoid is the issue of determining the length value in say characters when the prefix contains no characters. I am wondering if there is also a slightly subtler issue when we are calculating a length in characters but where a part of the length is in a different encoding from the other. For example the prefix contains 2 UTF16 (2 byte) characters and the content contains 2 UTF32 (4 byte) characters.. Do we just quote a length in characters regardless of encoding. eg. 4 characters. Or is this confusing .... 2.76 . Section 12.3.4 . When property prefixIncludesPrefixLength is ‘yes’there are some restrictions that need to be added to enable reliable lengths to be calculated: o If the prefix type is lengthKind 'implicit' or 'explicit' then the lengthUnits properties of both the prefix type and the element must be the same. Kind Regards, - Alex Alex Wood - Software Engineer - WebSphere Message Broker Development IBM DFDL Development MP 211, IBM UK Labs, Hursley Park, Winchester, Hants. SO21 2JN. Tel: Internal 246272, External 01962 816272 Notes: Alex Wood1/UK/IBM@IBMGB e-mail: wooda@uk.ibm.com 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