Basic Set Analysis should be in even the most junior QlikView developer's arsenal of tools. The ability to add modifiers, most frequently to the $ set, allows us to perform some very useful calculations that we either couldn't perform at all without Set Analysis, or that would have required us to do a lot more work.
We should already know about at least two of the identifiers that we can use in a Set Analysis expression: 1 and $. We also should know that the $ set is the default so that if there is no set identifier specified, then QlikView will use the $ set, which is just for current selections.
The following table shows a list of all the identifiers that you may come across: