Pros and cons of this approach

Pros

• It works

Cons

• Time consuming

  • Schema needs to be downloaded, converted, adjusted

  • This creates a branch of the original schemas which needs to be maintained and kept in sync with the source

  • Adding new language to our schema requires adjustments in the parent (XHTML) schema

• Knowledge demanding

  • Only someone how knows very well a complex language like W3C XML Schema is able to create and maintain such compound schemas

• Not reusable

  • We can't just reuse existing schemas for involved grammars (conversion, adjustments)

  • Our adjusted schemas are not easy to reuse for a different compound language. For example, in case XHTML should be embedded in SVG (other way around), we need to change a lot in our schemas and again create and maintain a branch.

• Difficult to understand

  • Constraints for the Compound language are hard-coded within constraints for the individual languages.

  • This is difficult to read and understand