Re: Need a language whiz: An XML Schema "specifies" howdata is

• A schema is the ruleset for an expert system that uses XML documents as inputs. 
• The expert system may use grammars, regular expressions, Xpaths, simple logic, lookups, etc.
  
• The output of the expert system is information that the user or technology environment finds useful. 
• This may include yes/no validity, implied or inferred properties such as type information, and rich or poor diagnostics.
• It is expedient if the ruleset can also be used for other purposes.
• This may include generative and data binding application.
  

(My original plan for Schematron was to move it in the direction of using logic by adding unification (and Michael Sperburg McQueen did something cool with Prolog if I remember), but it turned out XPath was so straightforward without it.)

Regards

Rick