Hook Points 
Hook points allow you to configure when the system executes hook point activities during the manufacturing process (see Hook Point Activity).
Hook point activities can be executed at various points at the site level or at the individual object level.
At the site level, the system can execute hook point activities whenever any operator throughout your entire site performs certain actions (see Site Level Hook Points)
At the object level, the system can execute hook point activities each time operators do the following:
For more information, see Object Level Hook Points.
Several hook points occur before or after the execution of POD button activities, such as Start, Complete, and Signoff.
Note
The system executes all code associated with a hook point in the same database transaction. The hook point transaction occurs with a single button activity, such as Start (PR500). If the hook point activity fails, the system rolls back, or cancels, the entire transaction. For example, if you associate Check Configuration (CT520) with the POST_START hook point and the components have not been assembled, the system rolls back the Start as well. This is true for all hook points.