A component of the identifier for the residue at which the
conformation segment begins.
This data item is a pointer to _atom_site.auth_comp_id in
the ATOM_SITE category.
Additional Descriptive Information for Depositors
A component of the identifier for the residue
at which the conformation segment begins. This
data item is a pointer to _atom_site.auth_comp_id
in the ATOM_SITE category.