This function is only available when connected to an Aster database.
The Cotangent function generates the cotangent (COT) of a Trigonometric argument. When dragging a Cotangent function into a variable, the following tree element is created.
Variable Creation > Input > Variables: SQL Elements pane - Trigonometric > Cotangent
Columns and/or other expressions can be moved into the (empty) branch of the tree. There are no special properties for the Cotangent operator.