Bukkit

Node Meanings

Drops.Enabled: Toggle if items can drop
Drops.Lowest Tier Only: Toggle if blocks drop items as though you broke it with your empty fists(which is the lowest tier)
Drops.Requirements.Tiered Boots: Toggle if the boot tier can prevent an item from dropping (such as whether diamond boots are required to obtain obsidian)
Break.Requirements.Tiered Boots: Toggle if boot tier can prevent block from breaking (such as wearing leather and attempting to break obsidian)
Break.Requirements.Tiered Damage: Toggle if increased fall-damage is required to break higher level blocks (such as obsidian)
Break.Requirements.Boots: Toggle if boots are required to be worn to break things by falling on them
Breakables.DEFAULT: Toggle if the default action for non-listed blocks is to break them
Breakables.ICE: Toggle if ice is breakable with fall damage
Breakables.GLASS: Toggle if glass is breakable with fall damage

You can add your own block to this list, such as obsidian!
Breakables.OBSIDIAN: would toggle if obsidian is breakable with fall damage