All suggestions are extremely welcome.
As always, a prettier HTML version of this will be posted shortly at 
http://purl.oclc.org/NET/xschema.
Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer / Cookies
2.6 XSchema Extensions
XSchema provides areas in which XSchema developers can provide supplemental 
information and metadata regarding XSchema components in both human- and 
machine-readable formats. Human-readable information is provided through the 
use of a subset of HTML that conforms to XML syntax, while machine-readable 
information may be provided through the XSC:More element.
2.6.1 Documentation Extensions
Human-readable documentation for XSchemas should be provided using the Itsy 
Bitsy Teeny Weeny Simple Hypertext format created by John Cowan.  The full DTD 
is available at http://www.ccil.org/~cowan/XML/ibtwsh.dtd.  Documentation that 
uses portions of the IBTWSH format may be included in the XSC:Doc element, a 
subelement available to all declarations.  The XSC:Doc element provides basic 
formatting options for XSchema documentation.
<!ENTITY % ibtwsh SYSTEM "http://www.ccil.org/~cowan/XML/ibtwsh.dtd">
%ibtwsh;
<!ELEMENT XSC:Doc %horiz.model;>
Any element allowed in the horiz.model set of elements (A, BR, SPAN, XML, 
CITE, CODE, DFN, EM, KBD, SAMP, STRONG, VAR, FONT, or parsed character data) 
may be used in the XSC:Doc element.
***- John - Any thoughts on namespaces for IBTWSH?  Any connections to style 
sheets, or should that be PIs like XML?
2.6.2 Other Extensions
The XSC:More element (coming soon to all elements that include XSC:Doc) 
provides an area which developers can use to create their own supplements to 
XSchema, defining content types more tightly than is possible through XSchema 
1.0. The XSC: More element has a simple ANY content model, though XSchema 
processors should prohibit the appearance of any elements from the XSchema 
namespace in this area.
<!ELEMENT XSC:More ANY;>