Group unbound set
Based on the nature of a bound group, the end of a bound group is determined without analyzing the data that follows it. However, if a group is not bound, the data that belongs to that group must be distinguishable from data that belongs to another type that might follow it in the data stream.
The unbound set of a choice or unordered group consists of the type of each component. The unbound set of a partitioned group consists of the unbound set of each unbound partition.