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In the Observation_fact table of the Clinical Research Chart of i2b2, the following columns are used to describe values associated with concepts:

     ValueType     ValType_CD (Varchar(50))

     NVal_num (number)

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Values are defined according to the ValueTypeValType_CD column, which can be construed as an identifier for the type of value object that fills out the rest of the above columns.   There are two identifiers that are used for medication modifiers:

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