Stan Kitsis wrote:
> In my experience API-level support is an order (or two) of magnitude more expensive than delivering UI apps.  First of all, the testing costs are much higher.  Second (and way more significant), once we realease an API, we will have to support it for 10 years or so - and this is extremely expensive.
>   
I hadn't heard that applications with User Interfaces were so cheap and 
easy to deliver.

Or that supplying a third-party developed and maintained library 
consisting of, say, two or three methods, and documented by existing 
XPath documentation, an ISO standard, material in multiple books, and 
many web articles, would be "extremely expensive".

In fact, I was once told that MS used Schematron as part of their 
regression testing for MSXML's XSLT implementation, so I suspect 
supplying Schematron might in fact be even easier for MS to do than it 
might be for your competitors. You might even see it a way of monetizing 
your regression tests! :-)  And I think customers would respond 
positively to MS and other vendors supporting ISO Schematron, because it 
both fills a common and constant need and because it increasingly is 
being adopted in government and industry standards. Schematron is moving 
from being the secret weapon of system developers, such as freight 
companies and legal publishers, to being the way that organizations and 
consortia who are serious about interoperability specify executable 
constraints with user-focused diagnostics.

To see where people are going with Schematron, here are three 
interesting sets of pages:
  "Schematron pushes the right buttons" on ACORD and Lloyds bank
 http://www.lloyds.com/News_Centre/Features_from_Lloyds/Schematron_pushes_the_right_buttons.htm
and
 http://www.marketreform.co.uk/Documents/Claims_pubs/London_Market_Implementation_of_ACORD_DRI_Messages.pdf
especially note section 4.3

NIST's Open Vulnerability and Assessment Language (OVAL)
 http://oval.mitre.org/language/download/schema/index.html
has a draft ISO Schematron schema at time of writing that is almost half 
a meg in size!

IBM's Business Information Conformance Statements (BICS), see
 http://www-128.ibm.com/developerworks/library/specification/x-bics20/BICSspec_v2.0.htm

Cheers
Rick Jelliffe