They take up a lot of space but the decisions below are pretty comprehensive.

13-2/1 Explanation of “Fairly Taking His Stance”
Q. Rule 13-2 states that a player must not improve the position or lie of his ball, the area of his intended stance or swing or his line of play or a reasonable extension of that line beyond the hole by moving, bending or breaking anything growing or fixed (including immovable obstructions and objects defining out of bounds). An exception permits a player to do so in “fairly taking his stance.” What is the significance of “fairly”?

A. Without “fairly,” the exception would permit improvement of position or lie, area of intended stance or swing or line of play by anything that could be said to be taking a stance. The use of “fairly” is intended to limit the player to what is reasonably necessary to take a stance for the selected stroke without unduly improving the position of the ball, his lie, area of intended stance or swing or line of play. Thus, in taking his stance for the selected stroke the player should select the least intrusive course of action which results in the minimum improvement in the position or lie of the ball, area of intended stance or swing or line of play. The player is not entitled to a normal stance or swing. He must accommodate the situation in which the ball is found and take a stance as normal as the circumstances permit. What is fair must be determined in the light of all circumstances.
Examples of actions which do constitute fairly taking a stance are:
• backing into a branch or young sapling if that is the only way to take a stance for the selected stroke, even if this causes the branch to move out of the way or the sapling to bend or break.
• bending a branch of a tree with the hands in order to get under the tree to play a ball.
Examples of actions which do not constitute fairly taking a stance are:
• deliberately moving, bending or breaking branches with the hands, a leg or the body to get them out of the way of the backswing or stroke.
• standing on a branch to prevent it from interfering with the backswing or stroke.
• hooking one branch on another or braiding two weeds for the same purpose.
• bending with a hand a branch obscuring the ball after the stance has been taken.
• bending an interfering branch with the hands, a leg or the body in taking a stance when the stance could have been taken without bending the branch.

13-2/1.1 Player Attempts to Take Stance Fairly But Improves Line of Play by Moving Interfering Growing Object
Q. A player’s ball lies under the branch of a tree. In attempting to take his stance fairly, the player improves his line of play by moving the branch with his body. Before playing, he realizes he could have taken his stance without moving the branch. He abandons his stance and the branch returns to its original position or is returned to its original position by the player. The player then approaches the ball from a different direction, takes his stance without disturbing the branch and makes his stroke. What is the ruling?

A. There is no penalty. When fairly taking his stance the player is required to take his stance in the least intrusive manner that results in the minimum improvement in the position or lie of the ball, area of intended stance or swing or line of play. However, as the branch moved as a result of the player’s attempt to take his stance fairly and was returned to its original position before the stroke was made, there is no penalty. Any doubt as to whether the branch returned to its original position should be resolved against the player.
The same principle would apply to fixed artificial objects (e.g., a boundary stake) if the position or lie of the ball, area of intended stance or swing or line of play is improved as a result of the player’s attempt to take his stance fairly but the object is returned to its original position before the player makes a stroke.