A main content of the paper is the syntax and semantics description of the schema language and the schema-specific procedures. But there are a lot of further schema languages like Schematron, DSD etc. What are the advantages of the presented syntax and semantics of the schema language? Why don't the procedure syntax and semantics based on these published schema languages? Is the expressivity/complexity of the presented schema language better scaled?

The same question can be asked about DemeterF?