-pdb_seq_num is used instead of auth_seq_num in get_ressers_mappings. Now resser2pdbresser contains all residues even the unobserved ones. This has been changed in PdbasePdb and CiffilePdb classes.

-pdb_strand_id not needed in the query in read_seq in PdbasePdb class. Asym_id and pdb_strand_id have 1-1 mapping in case sensitive mode.

-comments have been added about the entity_id-asym_id-pdb_strand_id 1-1-1 mapping and some filters in queries that are no longer necessary.