Minecraft wiki entry for Arrow, associated text:  crit: 1 or 0 (true/false) - Whether the arrow deals critical damage.
 damage: Damage multiplier of the arrow. Defaults to 2.0 for regular arrows, and is increased by a flat 0.5 if any level of Power is present on the bow. 0.5 is then added for each level of Power over the first (i.e Power I would result in 3.0, Power II would result in 3.5, etc.)[check the code]
 inBlockState: Optional. The block the arrow is in.
 Name: The resource location corresponding to the block.
 Properties: Optional. The block states of the block.
 Name: The block state name and its value.
 inGround: 1 or 0 (true/false) - Whether the arrow is stuck in the ground.
 life: Increments each tick when the arrow is not moving; resets to 0 if it moves. When it ticks to 1200, the arrow despawns.
 pickup: 0 = cannot be picked up by players. 1 = can be picked up by players in survival or creative. 2 = can be picked up by players only in creative.
 PierceLevel: The amount of remaining times this arrow can pierce through an entity.
 shake: Ticks until the arrow can be picked up by players. This is set to 7 when the arrow initially hits a block.
 ShotFromCrossbow: 1 or 0 (true/false) - Whether the arrow was shot from a crossbow. If inGround is true, this is always set to 0.
 SoundEvent: The sound event to play when hitting a block/mob, cannot use non-vanilla sound events.