var
sx,sy,sz:string;
lx,ty:extended;
rx,by:extended;
res:array[0..24] of extended;

begin
res[0]:=0;
res[1]:=50000;
res[2]:=49500;
res[3]:=25500;
res[4]:=9783;
res[5]:=4891.96980999999959749402;
res[6]:=2445;
res[7]:=1222;
res[8]:=611;
res[9]:=305;
res[10]:=152;
res[11]:=76;
res[12]:=38;
res[13]:=19;
res[14]:=9.5;
res[15]:=4.79999999999999982236;
res[16]:=2.39999999999999991118;
res[17]:=0;
res[18]:=0;
res[19]:=0;

lx:=-20037508+(getx*res[getz]*256);
rx:=-20037508+((getx+1)*res[getz]*256);

ty:=-15496570+((round(intpower(2,getz-1))-gety+1)*res[getz]*256);
by:=-15496570+((round(intpower(2,getz-1))-gety+0)*res[getz]*256);


ResultURL:=GetUrlBase+inttostr(getz)+'&BBOX='+RoundEX(lx,2)+','+RoundEX(by,2)+','+RoundEX(rx,2)+','+RoundEX(ty,2);
end.