There are special symbols used on the scorecard. You can note that some holes are circled or squared. The circles represent below-par holes and the squares above-par holes. A score that is neither circled nor squared is a par. Here is some explanation of such symbols:
No symbol - Par;
Circle - Birdie;
Filled in circle - Eagle or better;
Square - Bogey;
Filled in square - Double-bogey or worse.
Circles and squares on the scorecard making scoring in golf easier, especially for professional players.