Marketplace XML Vocabularies

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

Consider this: XML elements can be assigned standardized meaning and standardized behavior. For example, XSLT is an XML vocabulary with standardized meaning and behavior. An XSLT processor is an application that behaves in accordance with the behavior described by the XSLT specification. Since the publication of the XSLT specification, numerous XSLT processors have entered the marketplace, with names such as SAXON, XALAN, and Sabletron. Market forces drove some XSLT processors to rise to the top, while others dropped out of popularity.

Ditto for XML Schema.

I call XSLT and XML Schema "marketplace XML vocabularies."


Now consider (X)HTML. As far as I know, the (X)HTML specification does not specify the behavior of each element. For example, it does not specify how an application (e.g., browser) should behave upon encountering, say, a <ul> element. Yet, the (X)HTML vocabulary has a clear presence in the marketplace, in the form of browsers such as Firefox, IE, and Opera.

(X)HTML is a marketplace XML vocabulary.


QUESTIONS

1. What are the requirements for an XML vocabulary to find presence in the marketplace? Must the XML vocabulary have both standardized meaning and behavior? 

2. What are the characteristics of an XML vocabulary that incite vendors to create conforming applications and compete in the marketplace?

/Roger