Minecraft wiki entry for Argument_types, associated text: Must be a yaw angle, measured in degrees with float number. -180.0 for due north, -90.0 for due east, 0.0 for due south, 90.0 for due west, to 179.9 for just west of due north, before wrapping back around to -180.0. Tilde notation can be used to specify a rotation relative to the executor's yaw angle.