In TempoWeave, when this option is selected from the Tools command, you are first given a prompt as to whether or not to include structure only, structure and color or color only. Structure replacement means that the shaft number for each thread becomes the corresponding treadle for each weft pick. If there were more weft picks than warp threads prior to executing Tromp as Writ with structure, then the weft picks after executing the commond will equal the number of warp threads. If color only is copied, the treadling is not changed.