[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XHTML 2 Working Group won't be renewed?
On 9 Jul 2009, at 16:04 , Peter Hunsberger wrote: > On Thu, Jul 9, 2009 at 4:25 PM, Jim Tivy<jimt@bluestream.com> wrote: >> Not a good idea for an open interoperatable data format. > > If part of the spec is a way to figure out what delimiters are being > used in any given instance, then I'd argue the exact opposite. I > believe this was the case for SGML (anyone?) The definition of variant syntaxes is indeed allowed by SGML. At least one SGML processor supports it in full generality, or claimed to the last time I looked. I don't believe I can name a second parser that supports the feature in all its gory detail. The definition of variant syntaxes is hampered by the fact that ISO 8879 gives no particular guidance (that I can find) about how to ensure that the resulting grammar is unambiguous or can be parsed with bounded lookahead. Personally, I think that giving SGML the ability to define variant syntaxes may well have been necessary to get ISO 8879 (the SGML spec) finished and generate the necessary consensus around it; I suspect that some people were willing to work on it because they expected to use variant syntaxes a lot, and some people may have decided not to oppose it because of the variant syntax feature. But apart from things like the maximum length of names I don't remember the ability to support variant syntaxes being really important in SGML practice for most users. (Software Exoterica's work on the Cinemania project may be a counter-example, but I'm not sure they used a variant syntax.) In practice, faced with the choice of defining a variant concrete syntax that would make troff or DCF script (or even DCF GML) a conforming SGML syntax (and then what -- claiming that troff or DCF was a conforming SGML processor?), or just switching to the reference concrete syntax, the marketplace voted overwhelmingly with its feet and adopted the reference concrete syntax. Based on that experience, in this case I think Jim Tivy is right: variant concrete syntaxes are usually more trouble than they are worth. They impose a cost on all implementors (and all users) of the language, and provide benefit either to a very small number of users or to none. YMMV, of course. Michael Sperberg-McQueen -- **************************************************************** * C. M. Sperberg-McQueen, Black Mesa Technologies LLC * http://www.blackmesatech.com * http://cmsmcq.com/mib * http://balisage.net ****************************************************************
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] |
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|