Virtual Variables: Overview
Virtual Variables are a way of adding to the information that you can analyse within FastStats. An initial set of variables are created when the system is built using FastStats Designer and these can't be changed without rebuilding the system (which depending on how big the system is could take a long time and will probably require your FastStats administrator to perform the task). Virtual Variables can be used to add information to your system or to summarise or aggregate existing information into new forms. There are also techniques to create new score Virtual Variables using the Profile tool.
Virtual Variables are then treated in the same way as "normal" variables by the system and can be used in all the same ways. They will appear as variables within the System explorer window and can be dragged onto all the same places as a normal variable.
Unlike normal variables, Virtual Variables can also be updated once they have been created. Virtual Variables can also be deleted if they are no longer needed (whereas normal variables can only be removed by rebuilding the FastStats system).
When the FastStats system is rebuilt (usually as part of a scheduled update of the data) the Virtual Variables will no longer be available (as the data has now changed). These variables can then either be recreated by hand or recreated from either a URN Snapshot or by Rule using the Recreate Virtual Variables dialog.