It's indeed a string. I've made my own custom function where you can edit the accuracy.
function FindPortalByArrow:Boolean;
var
A, X, Y, ArrowSymbol: Integer;
InputAcc, OutputAcc: Extended;
begin
ClickNorth(0);
A:=0;
WriteLn('Counted gray colors: '+IntToStr(CountColorTolerance(10798276, 173, 279, 352, 292, 1))+'');
WriteLn('Counted red colors: '+IntToStr(CountColorTolerance(204, 208, 208, 324, 220, 1))+'');
repeat
ArrowSymbol := BitmapFromString(7, 15, 'meJzT9AzXxEAaAWkCVz8gI5IFT31' +
'ARhBB/n3vkRHxgiCRpe+JRG7r7/HPfoeMgCJqPonI4hCRxnpRuDhc' +
'BIJUPOOAIkASLgIXh7MBQZeURw==');
InputAcc := 0.5;
FindDeformedBitmapToleranceIn(ArrowSymbol, X, Y, MMX1, MMY1, MMX2, MMY2, 75, 0, True, OutputAcc)
FreeBitmap(ArrowSymbol);
if (OutputAcc > InputAcc) then
begin
WriteLn('We found the flicker arrow symbol, walking there!');
MMouse(X + RandomRange(3, 8), Y + RandomRange(10, 20), 2, 2);
Wait(25 + Random(75));
ClickMouse2(1);
Wait(100 + Random(100));
repeat
Wait(50 + Random(50));
until (IsMoving=False);
Result:=True;
end else
begin;
WriteLn('We haven`t been able to detect the flickering arrow symbol.');
Result:=False;
Inc(A);
Wait(250 + Random(500));
end;
until (OutputAcc > InputAcc) or (A>9);
end;
It also has a repeat loop with a random waiting time, because it is used to find a flickering symbol at the Great Orb Project.
Just play with that function, edit the bitmap, the names, etc. :P