Triclinic (hk0) layer at 84 K in: (a) the LS supercooled phase (LS-ord); (b) the LS disordered phase (LS-dis); (c) the magnified triclinic (hk0) layer at 84 K in the ordered LS phase (LS-ord) and (d)–(e) the disordered phase (LS-dis). In the LS-ord phase (c) only integer reflections are observed. In the LS-dis phase (d) additional reflections appear that violate the I-centring of twin (I) or are at non-integer positions for twin (I). The latter can be indexed with integer hkl for one of the other two twin domains. (e) All reflections of the LS-dis phase can be indexed using a single domain triclinic superstructure.