Reference catalogs
Reference catalogs are editor sections displaying a collection of objects referenced by the object for which the main editor is currently opened.
In the example image below, the Components Installed reference catalog displays components assigned to a system.

Reference list provides the following features within its parts:
Show/Hide search (A)
Click to expand and collapse the search functionality of the reference list.
Note that availability of particular search types is a matter of customization in the Catalog Customizer.
Reference list controls (B)
Control buttons for the reference list. Usually the following actions are present:
Edit
Opens an editor for the linked object currently selected in the catalog.
Search & assign
Opens a catalog of target objects for selection of an object to be linked.
Create
Opens an editor for a new target object creation.
Note: The availability of particular controls is a matter of customization in the Action Customizer.
Catalog (C)
List of the linked objects.
Reference catalog controls (D)
Controls influencing the display of listed objects.
Select between table view and tree view display. Note that availability of selectable view types may depend on catalog customization.
Select a historical aspect of listed objects display. This filters the catalog of linked objects according to the time-related validity of the link.All
Catalog displays both currently assigned objects and objects which were assigned in the past.
Historical
Catalog displays only objects which were assigned in the past (current date is after the lined objects' Assigned To date).
Current
Catalog displays only currently assigned objects (current date falls between Assigned From / Assigned To dates of the linked objects).
See the History aspect of reference catalogs topic for more information.
Reference catalog section/tab headers may display the number of referenced objects. Note that this feature is subject to view customization.