About marketing object references in approvals
You add marketing object references to approvals in the same way you add them to forms and grid fields. However, the options for searching for marketing objects are slightly different.
Simple search (Search tab)
The simple search screen in the marketing object selection box for approvals contains an additional drop-down list. You use this control to select a single type of marketing object for your search. A selection is required before you can begin the search.
Saved search (Browse tab)
The drop-down list of saved searches contains previously saved searches for all enabled marketing object types. For example, if you have marketing object types for Creatives and Envelopes, all saved searches for Creatives and Envelopes appear in the list.