?+_cell_measurement_radiation
    Description of the radiation used to measure the unit-cell data.
    See also _cell_measurement_wavelength.
    
+?_cell_measurement_wavelength
    The wavelength in angstroms of the radiation used to measure the
    unit cell. If this is not specified, the wavelength is assumed
    to be the same as that given in _diffrn_radiation_wavelength.
     
++_diffrn_radiation_probe
    (x-ray, neutron, electron, gamma)
    
    The nature of the radiation used (i.e. the name of the subatomic
    particle or the region of the electromagnetic spectrum).
    It is strongly recommended that this information be given,
    so that the probe radiation can be simply determined.

+?_diffrn_radiation_type
    The type of the radiation. This is used to give a more detailed
    description than _diffrn_radiation_probe and is typically a
    description of the X-ray wavelength in Siegbahn notation.

+?_diffrn_radiation_xray_symbol
    The IUPAC symbol for the X-ray wavelength for the probe radiation.
    
++_diffrn_radiation_wavelength
    The radiation wavelength in angstroms.
    
_diffrn_refln_wavelength
    The mean wavelength in angstroms of the radiation used to measure
    the intensity of this reflection. This is an important parameter
    for reflections measured using energy-dispersive detectors or the
    Laue method.

_diffrn_source
    The general class of the source of radiation.

_refln_wavelength
    The mean wavelength in angstroms of the radiation used to measure
    this reflection. This is an important parameter for data
    collected using energy-dispersive detectors or the Laue method.
    

