The Catalog menu includes the following options:

Include Selected Items Include the selected items in the catalog. 

Remove Selected Items Remove the selected items from the catalog. 

Scan to Catalog... Scan folders and files into a catalog without opening them in a contact sheet first. 

Sync Catalogs...Sync external changes you have made to photos in your catalog. 

Manage Catalogs...  Select active catalogs, reindex, or delete catalogs. 

Manage Shared Folders... Create a common path for shared folders between multiple computers. 

Catalog Status... Shows the status of catalog related tasks and allows you to end tasks that appear to be frozen. 

Catalog Preferences... Preferences specific to catalogs and the Organizer panel. 

Searchable Fields... Shows which metadata fields are searchable in catalogs

Example Searches... Shows example searches using Photo Mechanic Plus search query language. 

Manage Shared Folders... Use this if you use a shared folder of photos on more than one computer.