Hello again,
We also have XML schemas which provide a means of specifying element content of
XML documents in terms of data types, so that document type designers can
provide criteria for validating the content of elements as well as the markup
itself. XML schemas are written as XML files which follow the W3C XML Schema
recommendation, http://www.w3.org/TR/xmlschema-0/ .
[adapted from http://www.ucc.ie/xml/#schemas]
(There should be a cross-reference to dtds if poss.)
Just out of interest, and since it relates to earlier comments about different
interpretations of the term metadata in different fields, I think that both XML
metadata and the broader definition given below would come under the heading of
schema metadata given
http://www.ercim.org/publication/Ercim_News/enw35/intro.html
"Schema metadata is an intentional description of extensional instances.
Typically a schema consists of: database {name, size, security authorisations},
attributes {name, type, constraints}. Some of the constraints concern the
attribute domain, some are inter-attribute and as such may express
relationships. The schema intension has a formal logic relationship to the data
instances. This is important in ensuring data quality. It also provides a formal
basis for systems."
Phil.
Jenny Slater wrote:
>
> Hello,
>
> Firstly; I agree with Lorna Campbell's description of the remit of CETIS
> and the SIGs. There is obviously a need for us to set the survey in its
> context in an introductory paragraph, as Phil Barker suggested.
>
> Secondly; Thanks to Aida Slavic for clearing up the distinction between a
> scheme and a schema. The SCHEMAS definition will be entered into the CETIS
> encyclopedia when it is running properly (suitably referenced, of course!).
>
> I am personally very pleased to have such a workable definition. I had
> always got the impression that the two terms were used interchangeably! My
> own understanding on the difference between a schema and a scheme was from
> the Oxford English dictionary, which had given me the impression that a
> schema was simply a diagrammatic representation of a scheme, and I had
> trouble matching this to the use of the terms with regard to metadata.
>
> I also came across a recent definition of a schema as: "a set of
> statements, expressed in data definition language, that completely describe
> the structure of a document or a database." - Gilchrist, Alan (2002) "From
> Aristotle to the 'semantic web'", LA Record January 2001 vol 104(1).
>
> Whilst we're at it, has anyone else come across any other definitions of
> scheme and schema?
>
> All definitions will be entered into the CETIS encyclopedia since Lorna
> Campbell's recommendation that more than one definition ought to be allowed
> for each term, because the same terms are often used with slightly
> different meanings amongst different communities. (Please see Lorna's
> "Recommendations for CETIS encyclopedia" posting of 20 December 2001)
>
> best wishes
>
> Jenny
>
--
Phil Barker Learning Technology Advisor
ICBL, Department of Computing and Electrical Engineering
Heriot-Watt University, Edinburgh, EH14 4AS
Tel: 0131 451 3278 Fax: 0131 451 3327
Web: http://www.icbl.hw.ac.uk/~philb/
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