An item sub-library is a term which refers to a part of an item library and contains
a specific set of hook-up item data and associations. You create and manage item libraries
in the Reference Explorer, where item libraries are indicated with 
. An item library can contain any number of user-defined sub-libraries that you can
use when working with pipe specs. A new item library that you create automatically
contains a default sub-library, which you can use for assigning hook-up items if you
do not work with pipe specs. For more information on implementation of pipe specs
in Smart Instrumentation, see Pipe Specs. Sub-libraries are indicated with the 
icon.
You must set one item library as the active item library for your <plant>. After you
create hook-up items in this library, you can associate the appropriate sub-library
with hook-ups, and then, associate specific items with these hook-ups. In the Reference Explorer, the active item library is indicated with the 
icon.