ACTION ITEM: second rework of general section about extending/customizing schemas (http://www.w3.org/International/its/track/actions/1)

Hi there,

Here's a second modified version of the draft (see the "NEW>" stuff). The modifications should address
the input from Felix and Jirka. Please note, that we still need to find the material
for the "additional references".

Cheers,
Christian
===

The "How to do this" parts of this document often contain statements related
to schema creation or modification. The statements pertain to one of the
following state-of-affairs:

1. creating a new schema
2. modifying an existing schema 

The following aspects may need to be taken into account when working on both
of these topics:

1. Think twice before creating your own schema. Consider strongly existing
formats such as DITA, DocBook, Open Document Format, Office Open XML,
XML User Interface Language, Universal Business Language, ... Those formats 
have many insights 'built-in'.

2. The format itself should be carefully
checked with regard to modification capabilities. DocBook and DITA for
example come with their own set of features for adapting them to a special
need.

3. The mechanisms which you can or have to use depend on the schema
language (DTD, XSD, RelaxNG, ...). Namespace-based modularization of schemas
for example is difficult to realize for DTDs.

NEW> NVDL, which can amongst others be viewed as a meta-schema language, 
NEW> enables approaches which may be hard to realize otherwise.

4. Each schema language provides ways of extending or modifying existing
schemas. XSD for example provides statements such as "import",
"include", or "redefine" as well as mechanisms such as type
substitution/derivation.

5. Some processors do not implement support for all schema language
constructs.
Thus, a schema which works in one environment may not work in a different
one.

6. What is possible also depends on the features of the schema which the
modification is targeting. Examples:

- An XSD "redefine" for example only is only
possible if the modified schema has been created with named types.

- If you are working with XSD, your options depend on the question whether
the schemas involved define target namespaces (techniques such as working
"chameleon" or "proxy" schemas may be considered as solutions in certain
cases).

NEW>Note: The considerations above are only part of what you need to
NEW> 	take into account. You need to know a lot more when diving into
NEW>  schema modularization. Good additional reading is the following <>
===   

Christian Lieske
MultiLingual Technology Solutions (MLT)
SAP Language Services (SLS)
SAP Globalization Services
SAP AG
Dietmar-Hopp-Allee 16
D-69190 Walldorf
Germany
T   +49 (62 27) 7 - 6 13 03
F   +49 (62 27) 7 - 2 54 18
christian.lieske@sap.com
http://www.sap.com

Sitz der Gesellschaft/Registered Office: Walldorf, Germany

Vorstand/SAP Executive Board: Henning Kagermann (Sprecher/CEO), Léo
Apotheker (stellvertretender Sprecher/Deputy CEO), Werner Brandt, Claus
Heinrich, Gerhard Oswald, Peter Zencke

Vorsitzender des Aufsichtsrats/Chairperson of the SAP Supervisory Board:
Hasso Plattner 

Registergericht/Commercial Register Mannheim No HRB 350269

 

Diese E-Mail kann Betriebs- oder Geschäftsgeheimnisse oder sonstige
vertrauliche Informationen enthalten. Sollten Sie diese E-Mail irrtümlich
erhalten haben, ist Ihnen eine Kenntnisnahme des Inhalts, eine
Vervielfältigung oder Weitergabe der E-Mail ausdrücklich untersagt.

Bitte benachrichtigen Sie uns und vernichten Sie die empfangene E-Mail.
Vielen Dank.

 

This e-mail may contain trade secrets or privileged, undisclosed, or
otherwise confidential information. If you have received this e-mail in
error, you are hereby notified that any review, copying, or distribution of
it is strictly prohibited. Please inform us immediately and destroy the
original transmittal. Thank you for your cooperation.