The Week of Calendar function is supported, returning an integer 0-N, partial week in the beginning is 0. When dragging a Week of Calendar into a variable, the following tree element is created.
Variable Creation > Input > Variables: SQL Elements pane - Calendar > Week Of Calendar
Columns and/or other expressions that resolve to a date can be moved over the (empty) branch of the tree.
There are no special properties for the Week of Calendar function.