- From: Francis Norton <francis@redrice.com>
- Date: Wed, 14 Feb 2001 09:23:43 +0000
- To: Noah_Mendelsohn@lotus.com
- CC: XMLSchema Developer <xmlschemadev@hotmail.com>, xmlschema-dev@w3.org
OK, that's been FAQ'd - http://www.schemaValid.com/faq/xml-schema.html#c6 Noah_Mendelsohn@lotus.com wrote: > > >> Hi: > > >> Could some of the members of the mailing list share views > >> on what is a ur-definition ? what is the rationale behind it > >> and why it is called so ? > > >> Thanks in advance. > > >> best regards > >> Dev. > > Dear Mr. or Ms. Dev, > > >From [1] in the specification: > > "[Definition:] A distinguished ur-type definition is present in each XML > Schema, serving as the root of the type definition hierarchy for that > schema. The ur-type definition, whose name is anyType, has the unique > characteristic that it can function as a complex or a simple type > definition, according to context. Specifically, restrictions of the > ur-type definition can themselves be either simple or complex type > definitions." > > I think that says it, the ur-type is the root of the type hierarchy in > each schema. It's like "object" in Java, everything derives from it. As > to the name, I don't speak German, but I believe ur is an abbreviation for > über", which I believe translates as "above" or upper, and is commonly > used as a prefix adjective. So, ur-type is approximately supertype or > root type. I personally would not have gone for such an obscure name, > but.... Anyway, the actual string name you use for it in a schema > document is "anyType". e.g. > > <xs:element name="envelope" type="xs:anyType"/> > > The manifestation of the urType that admits only simple types is > anySimpleType: > > <xs:attribute name="thisAttrCanHoldAnyString" > type="xs:anySimpleType"/> > > The term urType shows up only when you read the specification itself > (historically we called it the urType, then added the convenience name, > and decided not to change the whole rest of the spec. Users see "anyType" > and "anySimpleType".) There are some subtleties in the type hierarchy, > but the above should get you through 99%+ of what you need to do. Hope > this helps. > > [1] http://www.w3.org/TR/xmlschema-1/#key-urType > > ------------------------------------------------------------------------ > Noah Mendelsohn Voice: 1-617-693-4036 > Lotus Development Corp. Fax: 1-617-693-8676 > One Rogers Street > Cambridge, MA 02142 > ------------------------------------------------------------------------
Received on Wednesday, 14 February 2001 04:24:19 UTC