Minecraft wiki entry for Classic_server_protocol, associated text: A pitch value of 0 means level and this value increases in a downward direction. 64 is down, and 192 is up. Values of 65 to 191 should never occur because the player cannot look further up or down than the 64 → 0, 255 → 192 range. However, the Minecraft Classic client does not ignore invalid values, so it is possible to make players' heads "upside-down".