Each workflow instance is a collection of sequencing rules related by temporal/control flow depenedencies. sequence rule A repeat clause. Minimum period of time after which the activity can be repeated. Maximum period of time before which the activity must be repeated. An observation group. a work group. a work block. this is the range object that restricts the property. this is a property of the empirical studies Set based ranges are unordered collections of enumeration codes from the enumerated value domain of the common data element to which the range refers. Each code may appear only once in the range.