The Annotate facility maintains two sets of internal
coordinates that are stored in the variable pairs (XLAST, YLAST) and
(XLSTT, YLSTT). One set of variables (XLAST, YLAST) stores coordinate
values that are generated by nontext functions and the other set (XLSTT,
YLSTT) stores coordinates generated by text functions. These two variable
pairs supply default values when the X or Y variable contains a missing
value.
Both pairs are initially
set to 0 and remain 0 until a function updates the values. You cannot
assign explicit values to these variables, but you can manipulate
their values with some of the Annotate functions.