It is possible to make hardcopy plots either interactively with GKS or via a metafile. Some devices accept acetate sheets, which allow transparencies to be produced for overhead projectors. The GKS plotter or metafile workstations operate just like any other, with an important exception. Namely, functions such as 'Delete Segment' will not undraw what has been output on the paper! Thus, when making a hardcopy, it is suggested that the picture to be plotted is produced first interactively on a terminal screen and stored in WISS (Workstation Independent Segment Storage). During this time the plotter or metafile workstation should be deactivated. When the picture is complete, and does not require further modification, then the plotter or metafile workstation may be activated and the WISS segments containing the picture sent to it by calling Associate SeGment to WorKstation (GASGWK).