The XSetDeviceButtonMapping request sets the mapping of the
specified device. If it succeeds, the X server generates a
DeviceMappingNotify event, and XSetDeviceButtonMapping returns
MappingSuccess. Element map[i] defines the logical button
number for the physical button i+1. The length of the list must
be the same as XGetDeviceButtonMapping would return, or a
BadValue error results. A zero element disables a button, and
elements are not restricted in value by the number of physical
buttons. However, no two elements can have the same nonzero
value, or a BadValue error results. If any of the buttons to be
altered are logically in the down state,
XSetDeviceButtonMapping returns MappingBusy, and the mapping is
not changed.

XSetDeviceButtonMapping can generate BadDevice, BadMatch, and
BadValue errors.

The XGetDeviceButtonMapping request returns the current mapping
of the specified device. Buttons are numbered starting from
one. XGetDeviceButtonMapping returns the number of physical
buttons actually on the device. The nominal mapping for a
device is map[i]=i+1. The nmap argument specifies the length of
the array where the device mapping is returned, and only the
first nmap elements are returned in map_return.

XGetDeviceButtonMapping can generate BadDevice or BadMatch
errors.

BadDevice
       An invalid device was specified. The specified device
       does not exist or has not been opened by this client via
       XOpenInputDevice. This error may also occur if the
       specified device is the X keyboard or X pointer device.

BadMatch
       This error may occur if an XGetDeviceButtonMapping or
       XSetDeviceButtonMapping request was made specifying a
       device that has no buttons.

BadValue
       Some numeric value falls outside the range of values
       accepted by the request. Unless a specific range is
       specified for an argument, the full range defined by the
       argument's type is accepted. Any argument defined as a
       set of alternatives can generate this error.

XChangeDeviceKeyboardControl(3), XChangeDeviceKeyMapping(3),
XChangeDeviceModifierMapping(3)