RE: support for substitution groups, support for redefines?

As far as I know Saxon supports redefines according to the spec, but:

(a) there are very few test cases in the W3C test suite so it's hard to be
sure

(b) by the nature of the facility, the design is very fragile

(c) even if you follow the spec and the product implements it correctly, you
can get into an awful mess

therefore I wouldn't recommend using it.

Substitution groups are fine, I don't see any problem with them.

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: xmlschema-dev-request@w3.org 
> [mailto:xmlschema-dev-request@w3.org] On Behalf Of Bryan Rasmussen
> Sent: 07 July 2005 08:33
> To: 'xmlschema-dev@w3.org'
> Subject: support for substitution groups, support for redefines?
> 
> 
> 	
> Hi
> Does anyone have a good overview of how well substitution groups and
> redefines are supported in various processors. The last big 
> project where I
> used redefines extensively about half a year ago I had to redo halfway
> through after running into too many problems, problems where 
> the redefine
> was proper and was supported by some processors but failed in 
> others, even
> more insidious where cases where I had redefined incorrectly and it
> functioned in some processors or in some test instances only 
> to fail later.
> This has put me off redefines, now I'm on something where 
> redefines and
> substitution groups are being proposed as the extensibility 
> mechanism. I've
> had misgivings about substitution groups, finding them somewhat overly
> complicated and have thus avoided them. How is their support?
> 
> Cheers
> Bryan Rasmussen
> 
>