A definition of a FHIR structure. This resource is used to describe the underlying resources, data types defined in FHIR, and also for describing extensions, and constraints on resources and data types.

An absolute URL that is used to identify this structure definition when it is referenced in a specification, model, design or an instance. This SHALL be a URL, SHOULD be globally unique, and SHOULD be an address at which this structure definition is (or will be) published.

So you can say, in a StructureDefinition, what the full extension URLs should be. This is required to allow hosting StructureDefinitions on multiple different servers, and to allow for the editorial process.

Formal identifier that is used to identify this StructureDefinition when it is represented in other formats, or referenced in a specification, model, design or an instance (should be globally unique OID, UUID, or URI), (if it's not possible to use the literal URI).

The identifier that is used to identify this version of the StructureDefinition when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the StructureDefinition author manually.

There may be multiple resource versions of the StructureDefinition that have this same identifier. The resource version id will change for technical reasons, whereas the stated version number needs to be under the author's control.

A free text natural language name identifying the StructureDefinition.

Not expected to be globally unique.

Defined so that applications can use this name when displaying the value of the extension to the user.

Applications don't have to use this name, but can always fall back to it. In the absence of a value for this element, use the name.

The status of the StructureDefinition.

Allows filtering of StructureDefinitions that are appropriate for use vs. not.

This StructureDefinition was authored for testing purposes (or education/evaluation/marketing), and is not intended to be used for genuine usage.

Allows filtering of StructureDefinitions that are appropriate for use vs. not.

The name of the individual or organization that published the structure definition.

Helps establish the "authority/credibility" of the structure definition. May also allow for contact.

Usually an organization, but may be an individual. This item SHOULD be populated unless the information is available from context.

Contacts to assist a user in finding and communicating with the publisher.

May be a web site, an email address, a telephone number (tel:), etc.

The name of an individual to contact regarding the structure definition.

If there is no named individual, the telecom is for the organization as a whole.

Contact details for individual (if a name was provided) or the publisher.

The date this version of the structure definition was published. The date must change when the business version changes, if it does, and it must change if the status code changes. In addition, it should change when the substantive content of the structure definition changes.

Additional specific dates may be added as extensions.

A free text natural language description of the StructureDefinition and its use.

This field can be used for things such as why the StructureDefinition was written, comments about misuse, instructions for clinical use and interpretation, literature references, examples from the paper world, etc. It is not a rendering of the StructureDefinition as conveyed in StructureDefinition.text. This item SHOULD be populated unless the information is available from context.

The content was developed with a focus and intent of supporting the contexts that are listed. These terms may be used to assist with indexing and searching of structure definitions.

Assist in searching for appropriate content.

Explains why this structure definition is needed and why it's been constrained as it has.

This element does not describe the usage of the structure definition (that's done in comments), rather it's for traceability of why the element is either needed or why the constraints exist as they do. This may be used to point to source materials or specifications that drove the structure of this data element.

A copyright statement relating to the structure definition and/or its contents. Copyright statements are generally legal restrictions on the use and publishing of the details of the constraints and mappings.

A set of terms from external terminologies that may be used to assist with indexing and searching of templates.

Assist in searching for appropriate StructureDefinitions.

The version of the FHIR specification on which this StructureDefinition is based - this is the formal version of the specification, without the revision number, e.g. [publication].[major].[minor], which is 1.6.0 for this version.

A StructureDefinition does not need to specify the target it applies to,as StructureDefinitions will often be valid across multiple versions of FHIR. FHIR tooling can determine whether a StructureDefinition is consistent with a particular StructureDefinition if desired.

An external specification that the content is mapped to.

An Internal id that is used to identify this mapping set when specific mappings are made.

The specification is described once, with general comments, and then specific mappings are made that reference this declaration.

An absolute URI that identifies the specification that this mapping is expressed to.

A formal identity for the specification being mapped to helps with identifying maps consistently.

A name for the specification that is being mapped to.

Comments about this mapping, including version notes, issues, scope limitations, and other important notes for usage.

Defines the kind of structure that this definition is describing.

Whether structure this definition describes is abstract or not - that is, whether an actual exchanged item can ever be of this type.

Abstract Resources cannot be instantiated - a concrete sub-type must be used. Abstract datatypes and extensions cannot be used in an instance. Flagging a constraint structure as abstract conveys design intent but makes no difference to how the structure definition is handled. Note that inline declared elements that are given the type "Element" in the profile, but have children described, are anonymous concrete types that specialise Element. Abstract is not relevant for logical models.

If this is an extension, Identifies the context within FHIR resources where the extension can be used.

Identifies the types of resource or data type elements to which the extension can be applied.

If the context is an element that can have multiple types, then use (e.g.) value[x] if the extension works on all choice types, or otherwise an enumeration of explicitly named elements if not. Note that a context of "string" doesn't mean that the extension can be used with one of the string patterns such as "id" etc.

The type this structure is describes. If the derivation kind is 'specialization' then this is the master definition for a type, and there is always one of these (a data type, an extension, a resource, including abstract ones). Otherwise the structure definition is a constraint on the stated type (and in this case, the type cannot be an abstract type).

Note that in the case of constraints, the type could be determined by chasing through the baseDefinition references until a concrete structure (derivation = specialization) is reached, or by looking at the path of the first element in the snapshot - if present - but providing the type directly makes for simpler tooling and indexing.

An absolute URI that is the base structure from which this type is derived, either by specialization or constraint.

If differential constraints are specified in this structure, they are applied to the base in a "differential" fashion. If there is no base, then the differential constraints cannot be provided (snapshot only). Differential structures are useful for the editing perspective, and snapshot structures are suitable for operational use. The FHIR Project provides a number of tools/services to populate snapshots from differential constraints. Logical Models have a base of "Element" or another logical model.

How the type relates to the baseDefinition.

If the definition is a specialization, then it adds new elements in the differential, and the snapshot includes the inherited elements.

If the definition is a constraint, then it can not define new elements, it can only make new rules about existing content (see Profiling Resources).

A snapshot view is expressed in a stand alone form that can be used and interpreted without considering the base StructureDefinition.

Captures constraints on each element within the resource.

A differential view is expressed relative to the base StructureDefinition - a statement of differences that it applies.

Captures constraints on each element within the resource.