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Re: Semantics of a list datatype derived from another list

From: Eddie Robertsson <eddie@allette.com.au>
Date: Wed, 21 Mar 2001 10:00:08 +1100
Message-ID: <3AB7E0F7.E50273E8@allette.com.au>
To: "Henry S. Thompson" <ht@cogsci.ed.ac.uk>
CC: Walt Yao <Walt.Yao@cl.cam.ac.uk>, xmlschema-dev@w3.org

"Henry S. Thompson" wrote:

> > I am implementing a Schema parser w.r.t the 24/10/2000 version, and
> > I run into a problem with the definition of a list datatype.  As
> > specified in 5.1.2, "a list datatype must be derived from an atomic
> > or a list datatype, know as the itemType of the list...".
> That's a known typo, will be corrected to 'atomic or _union_
> datatype'.
> Re another reply, you can include a list in a union, but that still
> doesn't allow  a list of lists -- a union used as the item type of a
> list can't contain any lists.

I've had I look at the new specification (PR) and it says that a list datatype
must be derived from an atomic type: List datatypes

"list datatypes are always derived. The value space of a list datatype is a set of
finite-length sequences of atomic values. The lexical space of a list datatype is
a set of literals whose internal structure is a white space separated sequence of
literals of the atomic datatype of the items in the list (where whitespace matches
S in [XML 1.0 (Second Edition)])."

My interpretation is that a list type must be derived from atomic types only and
not atomic or union types. Is this correct?

Received on Tuesday, 20 March 2001 18:00:48 UTC

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