Defined in file seqblock.asn
C++ class: CPDB_block
PDB-block ::= SEQUENCE { -- PDB specific descriptions
deposition Date , -- deposition date month,year
class VisibleString ,
compound SEQUENCE OF VisibleString ,
source SEQUENCE OF VisibleString ,
exp-method VisibleString OPTIONAL , -- present if NOT X-ray diffraction
replace PDB-replace OPTIONAL } -- replacement history