​There was a time, before 2019 to be exact, when touching the line of putt (now known as line of play) was most likely a violation of the Rules of Golf. Things have gotten a lot friendlier since the major revisions to the book came that year, but it’s still worth a quick refresher on what can get you into trouble on the putting green.Here’s one that might get your attention: You’re playing on a rainy day. Before replacing your ball and hitting a putt, you take the palm of your hand and rest it on the green on the line of play to check how much moisture there is in hopes of learning how hard to hit the ensuing putt.While it’s true that you’re now allowed to touch your line of play, including with things such as the flagstick, the butt end of your club or your index finger, you might also recall that there is a rule on the books that deals with “testing” the putting green.Rule 13.1e outlines what is allowed and not allowed. For example, you can’t rub or scrape the green to figure out if your putt will be downgrain and therefore slicker than if it was into the grain. The other thing you can’t do is roll a ball to test speed (hopefully that one is obvious). Do either of those things and you’re hit with the general penalty (two strokes or loss of hole in match play). You also can’t do these things on a “wrong green,” which is pretty much any other green on the course including practice greens. In other words, no testing! More Rules Reviews from Golf Digest Rules Review Rules of Golf Review: He rotated his golf ball without marking it. He says it’s OK because he didn’t lift it. True? Rules Review 5 rules most golfers get wrong Technology Got a rules question? The USGA is harnessing AI technology to get you fast, accurate answers Interestingly, there are things that are OK to do on the green even though it’s considered testing. One of those things is placing your palm down on the green to check for moisture. Clarification 13-1e/1 says that it’s fine, and so is rubbing a ball on the green to clean off mud/dirt, etc.There’s one more thing that might seem like you’re testing the green, but there’s no penalty for doing it. If you concede youropponent’snext putt and hit the ball away on the sameline of playas your next putt, it’s OK provided you didn’t do it deliberately to learn information about theputting green.Don’t get sneaky with that one. It would be pretty obvious if you hit it back to get a read.MORE GOLF DIGEST RULES REVIEWSWhat do I do if my ball just hit another ball on the green?What happens if my three-minute search for a lost ball gets interrupted?I hit myself with my own ball. Is that a penalty anymore?My ball ‘might’ be in a pond, but I can’t find it. Can I drop, add a penalty stroke and move on?What exactly is an embedded ball?Can you get relief from aeration holes?Does a ball have to be unplayable to declare it unplayable?I accidentally hit my ball with a practice stroke … does it count?I’m on the green. My opponent is not. Who’s a