In addition to the fields extracted from the data source, system fields are also produced by Qlik Sense. These all begin with "$" and can be displayed like ordinary fields in a visualization, such as a filter pane or a table. System fields are created automatically when you load data, and are primarily used as an aid in app design.
Available system fields
The following system fields are available:
|Contains all tables that are loaded.
|Contains all fields in the tables that are loaded.
|Contains the number of fields in each table.
|Contains the position of the fields in the tables.
|Contains the number of rows in the tables
None of the system fields can be manipulated in the script.
Using system fields in a visualization
System field data is associated. For example, if you add two filter panes, one with $Table and one with $Field, if you select a table, the $Field filter pane will show the fields in the selected table as possible values.
System fields are not included in field lists in the assets panel when you edit a sheet. They are included in the expression editor. If you want to use a system field in the assets panel, you need to reference it by typing it manually.
Example: In a dimension in the assets panel