Light Block

Light blocks are invisible blocks, primarily used for map makers, that can produce any light level.

Obtaining
Light blocks cannot be mined, or even targeted, similar to air. They do not attach to any block, meaning that breaking an adjacent block does not remove the light block. However, they can be broken by replacing with another block.

Light blocks are not in the player's Creative inventory. They can only be obtained using, with any damage value from 0 to 15. This value determines the block's light level.

Usage
Each light block (as a block or as an item) has an associated light level, which can be anything between 0 and 15 inclusive. In the player's inventory, light blocks use a "light bulb" texture, which glows if their light level is nonzero, and had an icon with the light level displayed.

When placed as blocks, light blocks are non-solid and completely invisible. Unlike barriers and structure void, they do not reappear when the player is holding another light block.

Light Source
Light blocks produce their associated light level.

Block data
Each light block has a data value between 0 and 15 inclusive, which determines its light level.

Trivia

 * Light blocks with light level 0 function as though they were air.