Item repair

Item Repair is a feature added in Beta 1.9 Pre-release 3 and allows players to repair damaged Tools or Items by combining them on a Crafting grid. Items can be placed anywhere on the crafting grid. The two tools the player is repairing must be of the same type and material for it to work. The usage points of the item that is repaired depends on the amount of usage points left in the sum of the two used items. The resulting item will have slightly more uses left than the two original items, more based on what material of the tool is used. Therefore, repairing is slightly more useful than just space conservation as what might be initially deduced. Also because it gets more uses, one can get more out of tools made out of non-renewable items.

Even if both items used are enchanted with the two exact same enchantments, the resulting tool will always be unenchanted, though the player can reenchant the tool.

Algorithm
The algorithm for determining uses left is as follows:

floor( Item A uses + Item B uses + (Max uses / 10)  ) (Floor means round down to the nearest integer.)

Example: Two stone axes with 32 uses.
 * 32 + 32 + 132/10 = 64 + (13.2) = 77

Facts
Tools made of different materials cannot be combined, e.g. a wood pickaxe and a stone pickaxe.