The ingredient constraints menu can be used to add additional constraints to (crafting recipe) ingredients. It should look like this:

Currently, there are 3 types of constraints:

• Durability constraints: the remaining durability of the ingredient must be above or below a specific percentage of its maximum durability (this only makes sense for breakable tools)
• Enchantment constraints: the ingredient must have specific enchantments, possibly between specific levels (this only makes sense for items that can be enchanted)
• Variable constraints: the ingredient must have a specific value for a specific variable. Variables are a rather advanced feature of this plug-in that make it possible to keep track of which upgrade recipes have been used on an item.