> ## Documentation Index > Fetch the complete documentation index at: https://docs.metriport.com/llms.txt > Use this file to discover all available pages before exploring further. # SubstanceSpecification > The detailed description of a substance, typically at a level beyond what is used for prescribing. ## Properties | Name | Required | Type | Description | | -------------------------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | identifier | No | [Identifier](/medical-api/fhir/data-types/identifier) | Identifier by which this substance is known | | type | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | High level categorization, e.g. polymer or nucleic acid | | status | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Status of substance within the catalogue e.g. approved | | domain | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | If the substance applies to only human or veterinary use | | description | No | string | Textual description of the substance | | source | No | Reference\<[DocumentReference](/medical-api/fhir/resources/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - role | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Role that the moiety is playing | | - identifier | No | [Identifier](/medical-api/fhir/data-types/identifier) | Identifier by which this moiety substance is known | | - name | No | string | Textual name for this moiety substance | | - stereochemistry | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Stereochemistry type | | - opticalActivity | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Optical activity type | | - molecularFormula | No | string | Molecular formula | | - amount\[x] | No | [Quantity](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - category | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | A category for this property, e.g. Physical, Chemical, Enzymatic | | - code | No | [CodeableConcept](/medical-api/fhir/data-types/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](/medical-api/fhir/resources/substancespecification) / [Substance](/medical-api/fhir/resources/substance)>, [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | A substance upon which a defining property depends (e.g. for solubility: in water, in alcohol) | | - amount\[x] | No | [Quantity](/medical-api/fhir/data-types/quantity), string | Quantitative value for this property | | referenceInformation | No | Reference\<[SubstanceReferenceInformation](/medical-api/fhir/resources/substancereferenceinformation)> | General information detailing this substance | | structure | No | SubstanceSpecificationStructure | Structural information | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - stereochemistry | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Stereochemistry type | | - opticalActivity | No | [CodeableConcept](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - identifier | No | [Identifier](/medical-api/fhir/data-types/identifier) | Substance identifier for each non-natural or radioisotope | | - name | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Substance name for each non-natural or radioisotope | | - substitution | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | The type of isotopic substitution present in a single substance | | - halfLife | No | [Quantity](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - method | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | The method by which the molecular weight was determined | | - type | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Type of molecular weight such as exact, average (also known as. number average), weight average | | - amount | No | [Quantity](/medical-api/fhir/data-types/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](/medical-api/fhir/resources/documentreference)>\[] | Supporting literature | | - representation | No | SubstanceSpecificationStructureRepresentation | Molecular structural representation | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - type | No | [CodeableConcept](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - code | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | The specific code | | - status | No | [CodeableConcept](/medical-api/fhir/data-types/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](/medical-api/fhir/resources/documentreference)>\[] | Supporting literature | | name | No | SubstanceSpecificationName | Names applicable to this substance | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - name | Yes | string | The actual name | | - type | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Name type | | - status | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | The status of the name | | - preferred | No | boolean | If this is the preferred name for this substance | | - language | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | Language of the name | | - domain | No | [CodeableConcept](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - authority | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Which authority uses this official name | | - status | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | The status of the official name | | - date | No | dateTime | Date of official name change | | - source | No | Reference\<[DocumentReference](/medical-api/fhir/resources/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](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - substance\[x] | No | Reference\<[SubstanceSpecification](/medical-api/fhir/resources/substancespecification)>, [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | A pointer to another substance, as a resource or just a representational code | | - relationship | No | [CodeableConcept](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/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](/medical-api/fhir/data-types/ratio) | For use when the numeric | | - amountType | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | An operator for the amount, for example "average", "approximately", "less than" | | - source | No | Reference\<[DocumentReference](/medical-api/fhir/resources/documentreference)>\[] | Supporting literature | | nucleicAcid | No | Reference\<[SubstanceNucleicAcid](/medical-api/fhir/resources/substancenucleicacid)> | Data items specific to nucleic acids | | polymer | No | Reference\<[SubstancePolymer](/medical-api/fhir/resources/substancepolymer)> | Data items specific to polymers | | protein | No | Reference\<[SubstanceProtein](/medical-api/fhir/resources/substanceprotein)> | Data items specific to proteins | | sourceMaterial | No | Reference\<[SubstanceSourceMaterial](/medical-api/fhir/resources/substancesourcematerial)> | Material or taxonomic/anatomical source for the substance | ## Search Parameters | Name | Type | Description | Expression | | ---- | ----- | ----------------- | -------------------------------- | | code | token | The specific code | SubstanceSpecification.code.code | ## Inherited Properties | Name | Required | Type | Description | | ----------------- | -------- | ------------------------------------------------------ | ------------------------------------------------------ | | id | No | string | Logical id of this artifact | | meta | No | [Meta](/medical-api/fhir/data-types/meta) | Metadata about the resource | | implicitRules | No | uri | A set of rules under which this content was created | | language | No | code | Language of the resource content | | text | No | [Narrative](/medical-api/fhir/data-types/narrative) | Text summary of the resource, for human interpretation | | contained | No | Resource\[] | Contained, inline Resources | | extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored | To view the FHIR specification for this resource, see [SubstanceSpecification](https://www.hl7.org/fhir/StructureDefinition/SubstanceSpecification).