To: "Henry S. Thompson (University of Edinburgh)" <email@example.com>, "David Beech
(Oracle Corp.)" <firstname.lastname@example.org>, "Murray
Maloney (Commerce One)" <email@example.com>, "Noah Mendelsohn
(Lotus Development Corporation)" <Noah_Mendelsohn@lotus.com>,
"David C. Fallside (IBM)" firstname.lastname@example.org
The following comments are (mainly) editorial comments by Joseph Reagle on the
XML Schema last call Working Draft .
- Glossary; and Model Groups, Model Group Definitions, and Element
- I find the distinction between these things confusing, perhaps it
could be simplified or more text could be spent on describing how these
things are different. Actually, I look forward to the glossary being
completed as this will help me in understanding the specification. See
 for more:
- 2.2 XML
Schema Abstract Data Model
- I could understand this chapter better if the 12 components listed
somehow corresponded more closely to the 2.2.* section headings.
Perhaps, a quick definition on each of the 12 components, or a move away
from the "primary" and "secondary" and "helper" designations (towards
others) if those terms aren't substantively used elsewhere.
- 2.5 Names
and Symbol Spaces
- The fact that you are using the same namespace "http://www.w3.org/1999/XMLSchema"
across different specifications with substantively different syntaxes
may cause problems for applications that expect the definition of a
dated name space to be stable. See  for more discussion on this
- Namespace Prefixes
- When trying to understand the specifications, I frequently found
myself bouncing between the primer, structures, and datatypes documents,
frequently using find or grep facilities to find bits of examples. Using
a consistent namespace prefix (xs: or xsd:) through all documents would
- 2.6 Schema-Related
Markup in Documents Being Schema-Validated
- Could the Schema Instance namespace somehow relate to the Schema
namespace? For instance, I'd find it easier to understand who defined
the schema instance namespace with something like:
- Appendix A (normative)
Schema for Schemas
- It would be useful for XML declarations to include more explicit
declarations of DTD and schema locations. For instance:
<!-- XML Schema schema for XML Schemas: Part 1: Structures -->
<!DOCTYPE schema PUBLIC "-//W3C//DTD XMLSCHEMA 19991216//EN"
version="Id: XMLSchema.xsd,v 1.1 2000/04/06 13:51:05 aqw Exp"
xsi:schemaLocation ="http://www.w3.org/1999/XMLSchema.xsd" >
- The more explicit representation of default values in schema component
definitions is useful. However, the many varied defaults can still be
confusing, perhaps this could be simplified, or a table could be
provided that includes all default values.
Advanced Concepts I: Namespaces, Schemas & Qualification
- This topic (not necessarily the exposition) is difficult to comprehend
with respect to both comprehending the concepts and as a potential
source of validation errors in instances I create. Perhaps some
guidelines such as, "If you want to create an instance that has no
prefixes in children elements then X; if you want to create an instance
... Y" so readers can easily jump-start their own schema writing.