A Data Source Context is in fact an HTML tag that is repeated dynamically in order to display information from a defined recordset (XML or Data Base). The Data Source Context is a repetitive region that imports all the information from a database. If you are querying a database and want to return only one record that matches the condition FirstName = Joe, then you need a WHERE condition in the recordset, but you do not need to add a data source context. The query will return all the records meeting that condition, then terminate. However, if you want to return all records in which FirstName = Joe, you will need to add a repetitive region so that all records in the database are searched and those meeting the condition will be returned.
In NetObjects Fusion 12, you may define as many repetitive regions as you want, but there are only three object types that can be configured as repetitive regions:
Layout Region. If the Layout Region is placed within a Multi Layout Region, then only one Layout Region can be a repetitive region.
Row of a Table. In NetObjects Fusion 12, only a line from a table can be a repetitive region.
Multi Layout Region. Any Multi Layout Region can be configured as a data context, if you have previously defined a database or an XML recordset. All the actions targeting a repetitive region on a Multi Layout Region have to target the container containing the Multi Layout Region (not the Multi Layout Region itself). The Multi Layout Region can be configured as a data source context only with PHP.