              A value that should be taken as a potential target value for the\
               torsion angle associated with the specified atoms, expressed as\
               the distance between the atoms specified by\
               _chem_link_tor.atom_id_1 and _chem_link_tor.atom_id_4 in the\
               referenced record in the CHEM_LINK_TOR list. Note that the\
               torsion angle cannot be fully specified by a distance (for\
               instance, a torsion angle of -60 will yield the same distance as\
               a 60 degree angle). However the distance specification can be\
               useful for refinement in situations in which the angle is already\
               close to the desired value.