Board Thread:Questions and Answers/@comment-211.30.50.41-20130701123317/@comment-4970029-20130701124708

Upgrade 0/2 means that the tower hasn't been upgraded on the first path and has been upgraded twice on the second path. A 0/2 Dart Monkey would mean that it has the upgrades Long Range Darts and Enhanced Eyesight, as those are the first two upgrades on the second path of upgrades.