That's such BS, Ryan. The word "mark" is the same word that causes you to put an identifying mark on your ball under Rule 6-5.
Go figure: the word mark means mark. Hmmm...what a shock.
Except in Far Hills.
Nice red herring. Yes, the ball has been approved. That's irrelevent. It's completely and utterly irrelevent. The issue isn't the ball. The issue is placing a mark that happens to be on the ball. Those are two totally different things....
You can't take that ball and throw it at another player's ball to stop it from reaching the hole, can you?
The fact that the ball is legal doesn't mean you get to do whatever you want with it. Sorry. That goes for clubs too. Take your legal driver and lay it next to your next 2 foot putt all the way to the hole and see how that goes over....
Rayn, you're spewing such garbage in defense of the indefensible. 
If it's not helpful, why the hell does everybody DO it?
Do me a favor: you have been trained by the best and you've had to interpret lots of rules. Please tell me what that last sentence of Rule 8-2(b) means in plain English. No spin. No interpretation. No made up nonsense. No advocating.
Just what does that sentence mean? Forget your own predispositions. Be objective. What does the sentence say?
Well, to humor this incredibly entertaining idiocity, I will engage you in your challenge. You've thrown down the proverbial gauntlet.
In order to strictly interpret Rule 8(2)(b), you must read all of 8(2) in its entirity.
8-2. Indicating Line of Play
• a. Other Than On Putting Green
Except on the putting green, a player may have the line of play indicated to him by anyone, but no one may be positioned by the player on or close to the line or an extension of the line beyond the hole while the stroke is being made.
Any mark placed by the player or with his knowledge to indicate the line must be removed before the stroke is made.
• b. On the Putting Green
When the player’s ball is on the putting green, the player, his partner or either of their caddies may, before but not during the stroke, point out a line for putting, but in so doing the putting green must not be touched. A mark must not be placed anywhere to indicate a line for putting.
Clearly, given the language of the rules, a line on the ball (even if drawn on the ball and not on the ball as part of the USGA certified manufacturing process), is not contemplated as being a mark and is not encompassed within that rule.
If, under your interpretation, a "mark" was intended to include, but not be limited to, a line on the ball, that mark could never be removed as is contempled under Rule 8(2)(a) and such inclusion of that language into Rule 8(2) would be redundant and unimportant. However, anyone who truly looks as this issue without your liberal and erroneous view of the word "mark" would clearly read this rule as merely banning a golfer or his caddy from placing an implement on the green to putt at in order to assist one in obtaining the desired end result of holing his putt in as little strokes as possible.
