1. Example shows when a DataSourceSelectionID is needed
No ID is needed (green circle) when there is only one column in the data source of the drop down (blue circles)
The selection ID is a name for a specific row in a data source that is being singled out based on user selections (yellow)
ID is needed below because there is more columns in the reference data source

2. When to use SelectionID in a tag string in a plugin
Form.Field.Table
Form.SelectionID.column
No need for SelectionID because data source only has one column