To assign a literal value to a property proceed as follows:

Click on Literal in the elements toolbar, and select a property to assign a literal value to (or use drag & drop).

To cancel the procedure, press Esc.

A box appears where you can enter the literal value. Press Enter to save the value.

You can change the value by double-clicking the box and entering a new value.
To delete the literal value, select the box and press the Del key, or select from the context menu.

If the direction of the output item (procurementAddress) changes from out to in, the literal is not of use anymore and is automatically deleted.