Unbound set of a sequence group

The unbound set does not include a type that could come last, if that type is a required occurrence. For example, if the type Comment Record could appear last and the component is specified as Comment Record (2:2), it is not in the unbound set, because the two occurrences of Comment Record are required. However, if Comment Record could appear last and the component is specified as Comment Record (1:2), then Comment Record is in the unbound set, since its second occurrence is optional.

To determine the unbound set of a group, start with the last component of the group and proceed backward up the component list. If a component is unbound or has a minimum range of zero, continue up the list. Stop at the first component that is bound or that is unbound but has a minimum range greater than zero. Essentially, a group's unbound set is everything that is not clearly defined at the end of the group.


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