Re: no proper description of prefixed. Recall that last Nov we discussed lengthKind='prefixed'. See http://www.ogf.org/pipermail/dfdl-wg/2007-November/000667.html This eliminates the keywords for prefix types and lengths of prefix fields. We just introduce predefined types like dfdl:prefix2 and dfdl:prefix4 which are very keyword-ish names. I guess this material is pending for inclusion into the spec still. Now back to our regularly scheduled email reply... I've attached a revised calculated value properties doc which incorporates suggestions from Alan, specifically, there's a new example, which is a 2-d array with nrows, ncols fields stored before it. I think this motivates the connection between outputValueCalc, and number of occurrences and occurs calculations nicely. .mikeb _____ From: Alan Powell [mailto:alan_powell@uk.ibm.com] Sent: Thursday, March 27, 2008 2:02 PM To: mbeckerle.dfdl@gmail.com Cc: dfdl-wg@ogf.org; dfdl-wg-bounces@ogf.org Subject: Re: [DFDL-WG] DFDL: Calculated Values section rewrite Mike A couple of comments on the using derived/representation nomenclature with OutputValueCalc and a couple of minor corrections. However I thought the Length Prefix example a bit odd as I would have expected a single HexBinary element rather than an array of bytes. And that got me thinking why isn't it just LengthKind=prefixed but I discovered that there is no proper description of prefixed. Was it intended to cover different kinds of length prefix or is it assumed to be 2 (or 4) bytes? 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 From: "Mike Beckerle" <mbeckerle.dfdl@gmail.com> To: <dfdl-wg@ogf.org> Date: 26/03/2008 16:39 Subject: [DFDL-WG] DFDL: Calculated Values section rewrite _____ My deliverable for the next draft (32) was to revise the calculated values section. I have rewritten it and the draft is attached. Of note: I have removed the troublesome "outputLengthCalc" property, as I no longer see a critical need for it. One of the examples computes the number of occurrences for a byte array, and I think that mechanism along with alignment is sufficient to handle the troublesome cases I was considering where size of padding had to be dynamically computed. The section now consists of a short table of definition, followed by illustrative examples, however, I think this is fine. The semantics of inputValueCalc and outputValueCalc aren't really that complex. They can be described in a paragraph. It is the motivation for them that is complicated, so I think examples in the spec, while sometimes considered problematic, are OK in this case. [attachment "calculated-value-properties.doc" deleted by Alan Powell/UK/IBM] -- dfdl-wg mailing list dfdl-wg@ogf.org <http://www.ogf.org/mailman/listinfo/dfdl-wg> http://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