A nested function of this form is entered at the Grid prompt:
outgrid = function1 ( function2 (ingrid) )
After completion, and immediately exiting GRID, a XYXY001 or similarly named grid will often remain behind.
If any other function or operation is executed after the nested one, and exiting GRID, the temporary grid is automatically cleaned up.
This is a known issue with ArcInfo Workstation.