This invention relates to golf clubs, and more particularly to the head of a golf club used for putting on the green. 
While using a putter on the green, a golfer usually positions himself very close to the ball, much closer than while using any other club to stroke a ball on a tee or the fairway.  Some golfers will also press their hands forward somewhat in front of the ball.  In other words, while addressing the ball, some golfers will tend to crouch close to the ball and tilt the club shaft slightly in the direction of the intended stroke.  This causes the face of the club head to be tilted slightly forward with the result that the face may not be visible to the golfer, at least in the case of a putter having little or no loft.  As a consequence of that tilt, the golfer will not have a reference for alignment of the club face except the upper edge of the club face.  However, due to the club head being tilted forward, the upper edge may no longer be a true reference.  This is particularly true of a putter having a face with an upper edge that inclines upwardly from heel to toe.  Tilting such a putter forward will cause the upper edge of the club face to swing counterclockwise at the toe, even though the face is still properly aligned, i.e., square with the direction of the intended stroke.  This swing of the upper edge causes the golfer to subconsciously correct the position of the head so that its upper edge will be square with the intended direction by turning the club head clockwise, thus opening the club face with the result that the stroke will be to the right of the intended direction. 
Frequently a line that is perpendicular to the face of the putter is provided as a reference on a surface of the club that will be visible under all circumstances.  While this line may be relied upon to some extent in squaring the club face with the intended direction for the ball, it is not as good a reference as the club face itself.  This is so because such a line is usually much shorter than the length of the club face.  Consequently, a small angle of misalignment will not be as easily noticed as when using the longer club face as a reference.  It would be desirable to provide a reference on the club face that will be visible even while the golfer addressing the ball presses his hands forward.