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== Composition Patterns ==

* [[Nested models for convenient grouping and composition]] ''' (Strawman - Charlie and Mark) '''
* [[Externally defined models with src attribute]] ''' (Strawman - Charlie and Mark) '''
* [[Custom XPath functions]], e.g sumover(), from host language ''' (Strawman - Erik) '''
* [[Same model item property on the same node]] (e.g. multiple constraints) ''' (Strawman - Nick and Leigh) '''