Minecraft wiki entry for History, associated text:  Health: Starts at 5, and currently only decreases as the item takes fire damage. When health reaches 0, the item is destroyed.
 Age: The amount of time an item has been "untouched" on the ground. After 2400 'ticks', or 2 minutes, the item is destroyed.
 Item: Item data
 id: Item or Block ID.
 Damage: The amount of wear each item has suffered. 0 means undamaged. When the Damage exceeds the item's durability, it breaks and disappears. Only tools and armor accumulate damage normally.
 Count: Number of items contained in this item drop entity. Any item can be stacked, including tools, armor, and vehicles. Range is 1-255.