There's a discussion in the Rules folder of our golf forum about the use of stymies. If you're not familiar with stymies, there's a good reason for that: Stymies disappeared from golf in 1952.
But before that, in singles match play, if an opponent's ball was in your way on the putting green, well, it was just in your way. Balls weren't marked and lifted (except under specific circumstances). You had to go around your opponent's ball, or over it.
I've been working lately on recaps of past PGA Championships, and stymies have come up in several. There's a good example of stymies in action in the recap of the 1929 PGA Championship.
Check out the forum discussion on stymies in the rules and in history.
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