# WSET > [HTML Version](wset_lit.htm) **WSET** [TRACKER](terminology.htm.md#tracker-in-terminology) is a Debug/MicroSabio module which keeps track of all output sent to the screen. In doing so, it manages to implement the -1,148 (save screen area) and -1,149 (restore screen area) [TCRT](terminology.htm.md#tcrt-in-terminology) calls for those terminal types that do not perform these functions in firmware. Tracking is enabled and disabled with the WSET command. A-Shell includes a functional equivalent of TRACKER that is permanently enabled, and so the -1,148 and -1,149 [TCRT](terminology.htm.md#tcrt-in-terminology) codes are always available for terminals on an A-Shell system. The WSET command is included mainly for compatibility and to prevent A-Shell rejecting it as an illegal command, though some of the operational switches are implemented. It always responds as the AMOS version does when tracking is already enabled: %TRACKER flag already set Allocated TRACKER buffer located - TRACKER 2.0C already installed The TRACKER /?, /M, and /N operational switches have been implemented.