Category: atom_site_rot_Fourier
Data type: char
Must appear in a looped list containing '_atom_site_rot_Fourier_id'
Permitted values:
x 'rotation around the a axis'
y 'rotation around the b axis'
z 'rotation around the c axis'
a1 'rotation around an arbitrary a1 axis'
a2 'rotation around an arbitrary a2 axis'
a3 'rotation around an arbitrary a3 axis'
A label identifying the rotation component, around a fixed point of a given rigid group whose modulation is being parameterized by Fourier series. a, b and c are the basic lattice vectors of the reference structure. For composites they refer to the reference structure of each subsystem. a1, a2 and a3 are defined by _atom_sites_rot_Fourier_axes_description.