Information describing a region in space/time, a data set, and a grid is collectively referred to as the "context." The current context may be examined with the commands SHOW DATA_SET, SHOW REGION, and SHOW GRID. The context may be set explicitly with the commands SET DATA_SET, SET REGION, and SET GRID.
The context may be modified for the duration of a single command with qualifiers to the command name (separated by slashes). The same qualifiers in square brackets may also modify single variables, changing the context only of that variable:
yes? PLOT/D=levitus_climatology temp, salt yes? CONTOUR rose[D=etopo20] yes? FILL/Z=0 temp[L=2] - temp[L=1]