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- type of constraint ADL (cADL): this type of matches right operand can be a value list , a value range, or a value range. Examples can be found from value list or value range section.
- URI: can be either terminology URI or EHR URI, or some other URI.
- embedded AQL query: means the within the curly braces, there is another AQL query which returns a result set.
These advanced operators are not yet supported by the grammar. The operator syntax is borrowed from ADL specifications. These are proposed to improve the richness and flexibility of AQL so that AQL syntax supports more complicated query scenarios.
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