You can view the current, next, and earlier versions of your reference catalog from the Catalog tab.
Current: This refers to the current version of your reference catalog. Click Catalog > View Current to view the current version. Any changes that you make, have to activated before they become a part of the current version of the catalog.
Next: This refers to the future revision of the catalog. Any changes that you make in the reference catalog will become effective in the future (on the date when the changes are scheduled to be activated). Click Catalog > Plan Next to create a new version of the catalog.