Data items in the PDBX_ENTITY_BRANCH_LIST category specify the list
               of monomers in a branched entity.  Allowance is made for the possibility
               of microheterogeneity in a sample by allowing a given sequence
               number to be correlated with more than one monomer ID. The
               corresponding ATOM_SITE entries should reflect this
               heterogeneity.
 
     loop_
    _pdbx_entity_branch_list.entity_id
    _pdbx_entity_branch_list.num
    _pdbx_entity_branch_list.comp_id
    _pdbx_entity_branch_list.hetero
    2 1  NAG   n
    2 2  GAL   n
    2 3  FUC   n
    2 4  FUC   n