ViceVersa

i read this page here http://greyminecraftcoder.blogspot.com.au/2014/12/block-models-texturing-quads-faces.html and i thought i understood how uv mapping worked. however on another one found here http://minecraft.gamepedia.com/Model it says the the down uv mapping for a standing torch is from [7,13,9,15] to [7.6.9.8]. If the down face is right in the middle of the block, is only 2x2 pixels big, and the entire thing only stands 10 pixels high i dont understand where the numbers 13 and 15 fit into this at all. If im not mistaken the down face is the x and z coordinates right? How exactly is uv mapping measured i just dont understand. Heres the json file im referring to File: torch.json { "ambientocclusion": false, "textures": { "particle": "#torch" }, "elements": [ { "from": [ 7, 0, 7 ], "to": [ 9, 10, 9 ], "shade": false, "faces": { "down": { "uv": [ 7, 13, 9, 15 ], "texture": "#torch" }, "up": { "uv": [ 7, 6, 9, 8 ], "texture": "#torch" } } }, { "from": [ 7, 0, 0 ], "to": [ 9, 16, 16 ], "shade": false, "faces": { "west": { "uv": [ 0, 0, 16, 16 ], "texture": "#torch" }, "east": { "uv": [ 0, 0, 16, 16 ], "texture": "#torch" } } }, { "from": [ 0, 0, 7 ], "to": [ 16, 16, 9 ], "shade": false, "faces": { "north": { "uv": [ 0, 0, 16, 16 ], "texture": "#torch" }, "south": { "uv": [ 0, 0, 16, 16 ], "texture": "#torch" } } } ] }

so in the blockstates json files, a lot of them have number values such as {"model": "tnt", "y": 90} what exactly is "y": 90 referring to?