Identifiers define the relationship between the set expression and the field values or expression being evaluated.
The following values can be used as identifiers:
| Identifier | Description |
| 1 | Represents the full set of all the records in the application, irrespective of any selections made. This means the whole data model. |
| $ | Represents the records of the current selection. The set expression {$} is thus the equivalent to not stating a set expression. For example: sum({$} [Product Value]) is the same as sum([Product Value]). |
| $n | Represents the n previous selections. Example: count ({$1} [User Id]) disregards the current selection made by the user and instead counts the [User Id] in the user's previous selection. |
| $_1 | Represents the next (forward) selection. This is only valid when more than two selections have been made. |
| BM01 | You can use any bookmark ID or bookmark name. |
| MyAltState | You can reference the selections made in an alternate state by its state name. Alternate states aren't available out of the box in the Qlik Sense September 2017 release or before. |