- Modularity of specifications is a Good Thing
- Specs can be re-used (eg, XSLT and XForms use XPath as their expression
- There are issues (for spec authors)
- Component specs may advance at different rates
- Need to be explicit about versions of referenced specs
- Clearly state what is required and what is optional
- Excessive optionality can reduce interoperability
- Can we also create modular, reusable test suites?