Minecraft wiki entry for Entity_format, associated text: : The entity's root tag.
 FallingBlock:
Tags common to block[show]
 Time: The number of ticks the entity has existed. If set to 0, the moment it ticks to 1, it vanishes if the block at its location has a different ID than the entity's FallingBlock.Name. If the block at its location has the same ID as its FallingBlock.Name when Time ticks from 0 to 1, the block is deleted, and the entity continues to fall, having overwritten it. When Time goes above 600, or above 100 while the block is below Y=1 or is outside building height, the entity is deleted. [needs testing]
 Tale: Deprecated. The numeric id of the block.
 Date: Deprecated. The metadata of the block.