Observer
An “observer’’ is one who is appointed by the Committee to assist a referee to decide questions of fact and to report to him any breach of a Rule. An observer should not attend the flagstick, stand at or mark the position of the hole, or lift the ball or mark its position.

Obstructions
An “obstruction’’ is anything artificial, including the artificial surfaces and sides of roads and paths and manufactured ice, except:

a) Objects defining out of bounds, such as walls, fences, stakes and railings;
b) Any part of an immovable artificial object which is out of bounds; and
c) Any construction declared by the Committee to be an integral part of the course.

An obstruction is a movable obstruction if it may be moved without unreasonable effort, without unduly delaying play and without causing damage. Otherwise it is an immovable obstruction.

Note: The Committee may make a Local Rule declaring a movable obstruction to be an immovable obstruction.

Out of Bounds
“Out of bounds’’ is beyond the boundaries of the course or any part of the course so marked by the Committee.

When out of bounds is defined by reference to stakes or a fence or as being beyond stakes or a fence, the out of bounds line is determined by the nearest inside points of the stakes or fence posts at ground level excluding angled supports.

Objects defining out of bounds such as walls, fences, stakes and railings, are not obstructions and are deemed to be fixed.

When out of bounds is defined by a line on the ground, the line itself is out of bounds.

The out of bounds line extends vertically upwards and downwards.

A ball is out of bounds when all of it lies out of bounds.
A player may stand out of bounds to play a ball lying within bounds.

Outside Agency
An “outside agency’’ is any agency not part of the match or, in stroke play, not part of the competitor’s side, and includes a referee, a marker, an observer and a forecaddie. Neither wind nor water is an outside agency.

Partner
A “partner’’ is a player associated with another player on the same side.
In a threesome, foursome, best-ball or four-ball match, where the context so admits, the word “player’’ includes his partner or partners.

Penalty Stroke
A “penalty stroke’’ is one added to the score of a player or side under certain Rules. In a threesome or foursome, penalty strokes do not affect the order of play.

Provisional Ball
A “provisional ball’’ is a ball played under Rule 27-2 for a ball which may be lost outside a water hazard or may be out of bounds.

Putting Green
The “putting green’’ is all ground of the hole being played which is specially prepared for putting or otherwise defined as such by the Committee. A ball is on the putting green when any part of it touches the putting green.

Referee
A “referee’’ is one who is appointed by the Committee to accompany players to decide questions of fact and apply the Rules. He shall act on any breach of a Rule which he observes or is reported to him.

A referee should not attend the flagstick, stand at or mark the position of the hole, or lift the ball or mark its position.

Rub of the Green
A “rub of the green’’ occurs when a ball in motion is accidentally deflected or stopped by any outside agency (see Rule 19-1).

Rule
The term “Rules’’ include:
The Rules of Golf;
Any Local Rules made by the Committee under Rule 33-8a and Appendix I; and
The specifications on clubs and the ball in Appendices