Uniform Semantics (2)

• Typed values
• XML Schema specifies isbn has user-defined type

/book/@isbn * 0.07

• Strict semantics
• Strict interpretation of typed values
• Type exception is fatal
• Errors may be detected statically or dynamically
• Flexible semantics
• Same as on last slide
• Attempts to convert user-defined ISBN value to double
• "Sandboxes" XPath 1.0 semantics