I only read this sign only after I played on the "play equipment". I think I'm in trouble... but shhh... don't tell anyone. :) I was driving past this field and noticed a guy standing more or less in the middle, whacking stones as far as he could, baseball-style. Technically I guess he's allowed to as it seems only golf is prohibited.
I wonder how many times a Metro officer has argued with a member of the public over technical interpretations of what's allowed in play parks and what's not. Technically, one is allowed to sleep in the park during the day, ride a motorbike as long as you don't wheelie and let your dog run free as long as they have a leash attached. I'm in no hurry to test the point, but if I had been challenged on the point of not being under 14 I may have considered arguing the point that I'm certainly under 14 inches. :D