Minecraft wiki entry for Model, associated text: The "parent"-tag uses "builtin/generated", so that the game uses the standard model of the torch, which has been generated out of the 2D graphic used for the item icon. The icon is specified with the "layer0"-tag and the texture, that has already been used for the block model, is used for the icon as well. As there is just one layer hard coded for the torch, there cannot be any more layers added. Furthermore, the display properties for the torch are specified, so that it displays correctly in every possible situation. The torch cannot be placed on a players head and uses the specified icon in the inventory, so there is no need to adjust the model for these situations. To line the model up with the players left or right hand in first and third person view, the model needs to be rotated, moved and scaled, which is done for each of the two situation separately.