The state of PONGO (global parameter values, AGI and PGPLOT) is returned
to a default state: all global parameters are reset to their default
values, the AGI database for the graphics device is cleared, and the
viewport is reset to the standard PGPLOT viewport. The global parameter
values for the PONGO data file (PONGO_DATA) and the polynomial
coefficients (PONGO_POLYCOEF) are not reset.
This command is an ICL hidden procedure using the SETGLOBAL
command and the CHANGE, CLEAR,
VIEWPORT and WORLD applications.