Should only elements be used or a combination of attributes and elements?

[wlthomas]

• If both are used what is the appropriate balance between their use?
  - Is verbosity a valid reason for the attributes?
  - If attributes are used how should they be limited?
  - use of xml:lang attribute
• Backwards compatibility issues:
  - CodeValue/ExternalContolledVocabularyEntry
  - International String or Structured International String
  - Attributes associated with identification