The Data Source Selection panel is the leftmost panel in the Ad Hoc Editor, titled as either:
- Domain: "Your specified Domain"
- Topic: "Your specified Topic"
The panel contains a list of available fields in the specified Topic or Domain. If you are using a Domain, fields may appear in nested sets that can be expanded or collapsed.
Available fields may be divided into two sections within the Data Source Selection panel: Fields and Measures.
To hide this panel, click the Hide Panel icon 
in the top left corner. Hiding a panel is helpful when arranging content in a large Ad Hoc view. Click the same icon on the minimized panel to expand it.