1. n. [Well Completions]

The smallest diameter present in a wellbore through which a tool string must pass to enable access to the operating depth or zone of interest. The minimum restriction determines the maximum tool string outside diameter and may influence the configuration of the assembled tools or equipment. The minimum restriction should be considered in both running and retrieving modes if any increase in tool string outside diameter is likely, such as when perforating or when using inflatable packers.