Tromp as Writ is a weaving term that means treadle as written in the weaving draft; the shaft numbers used in the threading are used to generate the treadle numbers in the weft.
In TempoWeave, when this option is selected from the Tools command, you are first given a prompt as to whether or not to include color as well as the shaft numbers. If cancel is pressed at this time, no changes will be made.
If OK is clicked on the above example, the weft sequence will be replaced entirely based on the threading. Color is only changed if "include color" is also checked: