Enables you to assign any number of hook-up items and hook-ups. When associating tag numbers with hook-ups that are assigned to the default sub-library, you can use any unassigned tag numbers. The software creates a default sub-library for every item library that you add in Smart Instrumentation. If you do not use any other sub-libraries, the default sub-library becomes the current item library in your plant. You cannot use the default sub-library for pipe spec assignment.