| identifier | No | Identifier | Identifier by which this substance is known |
| type | No | CodeableConcept | High level categorization, e.g. polymer or nucleic acid |
| status | No | CodeableConcept | Status of substance within the catalogue e.g. approved |
| domain | No | CodeableConcept | If the substance applies to only human or veterinary use |
| description | No | string | Textual description of the substance |
| source | No | Reference<DocumentReference>[] | Supporting literature |
| comment | No | string | Textual comment about this record of a substance |
| moiety | No | SubstanceSpecificationMoiety | Moiety, for structural modifications |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - role | No | CodeableConcept | Role that the moiety is playing |
| - identifier | No | Identifier | Identifier by which this moiety substance is known |
| - name | No | string | Textual name for this moiety substance |
| - stereochemistry | No | CodeableConcept | Stereochemistry type |
| - opticalActivity | No | CodeableConcept | Optical activity type |
| - molecularFormula | No | string | Molecular formula |
| - amount[x] | No | Quantity, string | Quantitative value for this moiety |
| property | No | SubstanceSpecificationProperty | General specifications for this substance, including how it is related to other substances |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - category | No | CodeableConcept | A category for this property, e.g. Physical, Chemical, Enzymatic |
| - code | No | CodeableConcept | Property type e.g. viscosity, pH, isoelectric point |
| - parameters | No | string | Parameters that were used in the measurement of a property (e.g. for viscosity: measured at 20C with a pH of 7.1) |
| - definingSubstance[x] | No | Reference<SubstanceSpecification / Substance>, CodeableConcept | A substance upon which a defining property depends (e.g. for solubility: in water, in alcohol) |
| - amount[x] | No | Quantity, string | Quantitative value for this property |
| referenceInformation | No | Reference<SubstanceReferenceInformation> | General information detailing this substance |
| structure | No | SubstanceSpecificationStructure | Structural information |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - stereochemistry | No | CodeableConcept | Stereochemistry type |
| - opticalActivity | No | CodeableConcept | Optical activity type |
| - molecularFormula | No | string | Molecular formula |
| - molecularFormulaByMoiety | No | string | Specified per moiety according to the Hill system, i.e. first C, then H, then alphabetical, each moiety separated by a dot |
| - isotope | No | SubstanceSpecificationStructureIsotope | Applicable for single substances that contain a radionuclide or a non-natural isotopic ratio |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - identifier | No | Identifier | Substance identifier for each non-natural or radioisotope |
| - name | No | CodeableConcept | Substance name for each non-natural or radioisotope |
| - substitution | No | CodeableConcept | The type of isotopic substitution present in a single substance |
| - halfLife | No | Quantity | Half life - for a non-natural nuclide |
| - molecularWeight | No | SubstanceSpecificationStructureIsotopeMolecularWeight | The molecular weight or weight range (for proteins, polymers or nucleic acids) |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - method | No | CodeableConcept | The method by which the molecular weight was determined |
| - type | No | CodeableConcept | Type of molecular weight such as exact, average (also known as. number average), weight average |
| - amount | No | Quantity | Used to capture quantitative values for a variety of elements. If only limits are given, the arithmetic mean would be the average. If only a single definite value for a given element is given, it would be captured in this field |
| - molecularWeight | No | | The molecular weight or weight range (for proteins, polymers or nucleic acids) |
| - source | No | Reference<DocumentReference>[] | Supporting literature |
| - representation | No | SubstanceSpecificationStructureRepresentation | Molecular structural representation |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - type | No | CodeableConcept | The type of structure (e.g. Full, Partial, Representative) |
| - representation | No | string | The structural representation as text string in a format e.g. InChI, SMILES, MOLFILE, CDX |
| - attachment | No | Attachment | An attached file with the structural representation |
| code | No | SubstanceSpecificationCode | Codes associated with the substance |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - code | No | CodeableConcept | The specific code |
| - status | No | CodeableConcept | Status of the code assignment |
| - statusDate | No | dateTime | The date at which the code status is changed as part of the terminology maintenance |
| - comment | No | string | Any comment can be provided in this field, if necessary |
| - source | No | Reference<DocumentReference>[] | Supporting literature |
| name | No | SubstanceSpecificationName | Names applicable to this substance |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - name | Yes | string | The actual name |
| - type | No | CodeableConcept | Name type |
| - status | No | CodeableConcept | The status of the name |
| - preferred | No | boolean | If this is the preferred name for this substance |
| - language | No | CodeableConcept[] | Language of the name |
| - domain | No | CodeableConcept[] | The use context of this name for example if there is a different name a drug active ingredient as opposed to a food colour additive |
| - jurisdiction | No | CodeableConcept[] | The jurisdiction where this name applies |
| - synonym | No | [] | A synonym of this name |
| - translation | No | [] | A translation for this name |
| - official | No | SubstanceSpecificationNameOfficial | Details of the official nature of this name |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - authority | No | CodeableConcept | Which authority uses this official name |
| - status | No | CodeableConcept | The status of the official name |
| - date | No | dateTime | Date of official name change |
| - source | No | Reference<DocumentReference>[] | Supporting literature |
| molecularWeight | No | [] | The molecular weight or weight range (for proteins, polymers or nucleic acids) |
| relationship | No | SubstanceSpecificationRelationship | A link between this substance and another, with details of the relationship |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | Extension[] | Additional content defined by implementations |
| - modifierExtension | No | Extension[] | Extensions that cannot be ignored even if unrecognized |
| - substance[x] | No | Reference<SubstanceSpecification>, CodeableConcept | A pointer to another substance, as a resource or just a representational code |
| - relationship | No | CodeableConcept | For example “salt to parent”, “active moiety”, “starting material” |
| - isDefining | No | boolean | For example where an enzyme strongly bonds with a particular substance, this is a defining relationship for that enzyme, out of several possible substance relationships |
| - amount[x] | No | Quantity, Range, Ratio, string | A numeric factor for the relationship, for instance to express that the salt of a substance has some percentage of the active substance in relation to some other |
| - amountRatioLowLimit | No | Ratio | For use when the numeric |
| - amountType | No | CodeableConcept | An operator for the amount, for example “average”, “approximately”, “less than” |
| - source | No | Reference<DocumentReference>[] | Supporting literature |
| nucleicAcid | No | Reference<SubstanceNucleicAcid> | Data items specific to nucleic acids |
| polymer | No | Reference<SubstancePolymer> | Data items specific to polymers |
| protein | No | Reference<SubstanceProtein> | Data items specific to proteins |
| sourceMaterial | No | Reference<SubstanceSourceMaterial> | Material or taxonomic/anatomical source for the substance |
