Table 1: chem_comp category
Token Definition Example
_chem_comp.id The alphanumeric code for the chemical component. 
HYP
_chem_comp.name The name of the chemical component. 
4-HYDROXYPROLINE
_chem_comp.type The type of monomer. 
L-peptide linking
_chem_comp.pdbx_type A preliminary internal classification used by PDB. 
ATOMP
_chem_comp.formula The chemical formula of the chemical component. 
C5 H9 N1 O3'
_chem_comp.mon_nstd_parent_comp_id The identifier for the parent component of the nonstandard component. May be a comma-separated list if this component is derived from multiple components. 
PRO
_chem_comp.pdbx_synonyms Synonym list for the non-standard residue. 
HYDROXYPROLINE
_chem_comp.pdbx_formal_charge The formal charge on the chemical component. 
+1
_chem_comp.pdbx_initial_date Date the chemical component was added to the database. 
yyyy-mm-dd
_chem_comp.pdbx_modified_date Date that the component was last modified. 
yyyy-mm-dd
_chem_comp.pdbx_ambiguous_flag For ligands with unconventional bonding (i.e. ligands with transition metal complexes). 
code
_chem_comp.pdbx_release status Status of ligand (released, hold, obsoleted). 
yyyy-mm-dd
_chem_comp.pdbx_replaced_by Identifies the _chem_comp.id of the new component that has replaced this component. 
3-letter identifier
_chem_comp.pdbx_replaces Identifies the _chem_comp.id of the component this entry replaces. Converse of _replaced_by. 
3-letter identifier
_chem_comp.formula_weight Formula mass of the chemical component in Daltons. 
131.131
_chem_comp.one_letter_code Reports the one-letter code of the component, if applicable. 
one-letter identifier
_chem_comp.three_letter_code Reports the three-letter code of the component, if applicable. 
ATP
_chem_comp.pdbx_model_coordinates_details Provides additional details about the model coordinates in the component definition. 
text
_chem_comp.pdbx_model_coordinates_missing_flag This data item identifies if model coordinates are missing in this definition 
Y or N
_chem_comp.pdbx_ideal_coordinates_details Identifies the source of the ideal coordinates in the component definition. 
text
_chem_comp.pdbx_ideal_coordinates_missing_flag Identifies if ideal coordinates are missing in this definition. 
Y or N
_chem_comp.pdbx_model_coordinates_db_code Identifies the PDB database code from which the heavy atom model coordinates were obtained. 
PDB entry id
_chem_comp.pdbx_processing_site Identifies the deposition site that processed this chemical component defintion. 
RCSB PDB, PDBj, PDBe