Every workstation in a GKS output level 1 or 2 implementation has associated with it a Workstation Dependent Segment Store (WDSS). At the time a segment is created, it is stored in the WDSS of all open and activated workstations. The WDSS may be physically located in the Graphics Terminal, in which case there can be a substantial improvement in performance. Of course, care must be taken not to exceed the available memory space.
In addition to WDSS, GKS output level 2 implementations have also a Workstation Independent Segment Store (WISS). WISS is a mechanism for storing segments in a workstation-independent way, and allows segments to be re-used and manipulated on different workstations at different times. WISS is treated like any another workstation, just like a terminal for example, and if it is open and activated when a segment is created, then that segment will be stored there as well as on the WDSSs of the other active workstations. For example, one might store an object in WISS at the same time as displaying it on a terminal. Then, at a later time, it would be possible to make a hardcopy of the object by extracting the segment(s) in which it was stored from the WISS and copying it (them) to a plotter. A transformation or segment deletion affects the segment wherever it is stored.
Before primitives are stored in WDSS or WISS they first undergo the normalization transformation currently in force. Also, when a segment is created, the current clipping rectangle together with the clipping flags, are stored in the segment, but clipping is not performed on the primitives when they are stored, but only when the contents of the segment are output to a device.