The group of elements that are part of a wellbore interval set. A wellbore interval set represents ALL of the interesting intervals and points in one wellbore. That is, it represents a container in a wellbore for the purpose of collecting all intervals and points. As such, the container has no identity outside of that provided by the wellbore's own identity. A perforated interval. An interesting classified interval in a wellbore. An interesting classified point in a wellbore. A constant diameter borehole in a wellbore.