Data Sources are configured with "Source Object" - which is a "variable". This is typically the Object ID that is to be used as a Parent Object for a subsequent List / Data source. For example, click on an a member of staff (Object ID123456) in a list of all your Staff and open a second list the Tasks this member of staff has performed. Then click on another member of staff and see a list of all their Tasks.
The list of Tasks is generated using the Object ID of the entry clicked - we call this the "FormsKey" variable. There are four system variables you have direct access to. These are explained further, below;
Additionally you can create your own "Form Variables", accessing other methods that are built into XPOR. This is also explained below.
In some cases you may need to do something different than the standard XPOR System Variables will enable. In which case you can simply create your own Variable and
The "object" object variable (!) is going to focus the next grid form on the object that has been clicked, For example, if you have arranged your Books into Categories and put your list of categories into a Menu, then, when you click a partiucular category in the menu, you may want to display all of the books in that category. Easily done with a Grid. But the grid needs to understand which category was clicked.
In the example of the FormsKey System Variable, it would be straightforward to click on a Grid Form entry - category123, and carries its' object ID to the next grid - to seed its' data source and return all of its books.
The Menu doesn't have a FormsKey - but is does know what has been clicked! The Menu is simply listing out the selected objects - so each menu item is based on an OBJECT. In this case it is listing out the know you have clicked the "object"option.