Global rotation of the nonrotating origin

We demonstrate the global secular rotation of the Celestial Ephemeris Origin (CEO), the nonrotating origin (NRO) for Earth's equator adopted recently by the IAU. The current speed of this global rotation is as high as -4."15 yr(-1), where the minus sign indicates that the CEO rotates clockwise with respect to the inertial frame when viewed from the north celestial pole. Such secular rotation does not exist for some geometrically defined longitude origins. We think that the existence of a global secular rotation means that the CEO, and the NRO in general, is not appropriate to be specified as the x-axis of a celestial coordinate system.