5.4.9: Slightly changed [enchantmentid] so that the string id no longer needs to be quoted.
6.0.0: The namespace for an enchantment id is no longer required. For example, minecraft:sharpness can be written as just sharpness.
11.1.7: Performance-wise, /setenchantmentlevel with a specific enchantment ID will no longer loop through the entire enchantment registry for each applied enchantment on the item in main-hand as that was pretty redundant.