Re: [relax-ng] Discrepancy in treatment of pattern facet

[James Clark <jjc@jclark.com>]

In XSD, you get the effect of all patterns by using xs:restriction, e.g. if 
S1 specifies P1 and S2 is derived by restriction from S2 and specifies P2, 
then a valid string must match both P1 and P2.  See Part 2, section 4.3.4.3.

If we made multiple patterns mean any, then we wouldn't be able to 
represent this in RELAX NG.  On the other hand, with the choice we made we 
can represent all with multiple patterns and we can do any simply by 
combining multiple regexes into a single regex by using |.

--On 18 June 2002 15:00 -0400 John Cowan <jcowan@reutershealth.com> wrote:

> The XSD Guidelines says:
>
># If the pattern parameter is specified more than once for a single data
># element, then a string matches the data element only if it matches all
># of the patterns. It is an error to specify a parameter other than pattern
># more than once for a single data element.
>
> But XS part 2 says:
>
># If multiple pattern element information items appear as children
># of a simpleType, the values should be combined as if they appeared
># in a single regular expression as separate [choice] branches.
>
> Why this incompatibility?  RNG says "all", XSD says "any".
>
> --
> John Cowan <jcowan@reutershealth.com>     http://www.reutershealth.com
> I amar prestar aen, han mathon ne nen,    http://www.ccil.org/~cowan
> han mathon ne chae, a han noston ne 'wilith.  --Galadriel, _LOTR:FOTR_
>
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