#100 = 10;  /non vacant/  10
#101 = ? /vacant/

g00 x#100 y#101

G00 X10. Y;
G01 Z-10. F100;
X#100

#101 = 44;
#101 = #100;
#101 = [[#100+44]*SIN[#100]]*SQRT[3];
#100 = #101;

-----------------------------
/10 G00 X10.

???
IS #105 VACANT?

VACANT = 100;
NON-VACANT = ;

------------------------------------------
IF [#100 EQ #0] THEN #100=100;
IF [#101 EQ #0] THEN #101=100;
G00 X#100 Y#101;