A ValueSet resource instances specifies a set of codes drawn from one or more code systems, intended for use in a particular context. Value sets link between CodeSystem definitions and their use in coded elements.

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

The only time that a resource does not have an id is when it is being submitted to the server using a create operation.

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

The base language in which the resource is written.

Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope.

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags In their meta elements, but SHALL NOT have security labels.

May be used to represent additional information that is not part of the basic definition of the resource. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the resource, and that modifies the understanding of the element that contains it. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

An absolute URI that is used to identify this value set when it is referenced in a specification, model, design or an instance; also called its canonical identifier. This SHOULD be globally unique and SHOULD be a literal address at which at which an authoritative instance of this value set is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the value set is stored on different servers.

Allows the value set to be referenced by a single globally unique identifier.

Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred. Multiple instances may share the same URL if they have a distinct version.

The determination of when to create a new version of a resource (same url, new version) vs. defining a new artifact is up to the author. Considerations for making this decision are found in Technical and Business Versions.

A formal identifier that is used to identify this value set when it is represented in other formats, or referenced in a specification, model, design or an instance.

Allows externally provided and/or usable business identifiers to be easily associated with the module.

Typically, this is used for identifiers that can go in an HL7 V3 II (instance identifier) data type, and can then identify this value set outside of FHIR, where it is not possible to use the logical URI.

The identifier that is used to identify this version of the value set when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the value set author and is not expected to be globally unique. For example, it might be a timestamp (e.g. yyyymmdd) if a managed version is not available. There is also no expectation that versions can be placed in a lexicographical sequence.

There may be different value set instances that have the same identifier but different versions. The version can be appended to the url in a reference to allow a reference to a particular business version of the value set with the format [url]|[version].

A natural language name identifying the value set. This name should be usable as an identifier for the module by machine processing applications such as code generation.

Support human navigation and code generation.

& A name should be provided unless the value set is a contained resource (e.g. an anonymous value set in a profile). Most registries will require a name.

A short, descriptive, user-friendly title for the value set.

This name does not need to be machine-processing friendly and may contain punctuation, white-space, etc.

The status of this value set. Enables tracking the life-cycle of the content.

Allows filtering of value sets that are appropriate for use versus not.See also the valueset-workflowStatus extension for additional status information related to the editorial process.

A Boolean value to indicate that this value set is authored for testing purposes (or education/evaluation/marketing) and is not intended to be used for genuine usage.

Enables experimental content to be developed following the same lifecycle that would be used for a production-level value set.

Allows filtering of value sets that are appropriate for use versus not.

& (e.g. the 'content logical definition').

Note that this is not the same as the resource last-modified-date, since the resource may be a secondary representation of the value set. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

The name of the organization or individual that published the value set.

Helps establish the "authority/credibility" of the value set. May also allow for contact.

Usually an organization but may be an individual. The publisher (or steward) of the value set is the organization or individual primarily responsible for the maintenance and upkeep of the value set. This is not necessarily the same individual or organization that developed and initially authored the content. The publisher is the primary point of contact for questions or issues with the value set. This item SHOULD be populated unless the information is available from context.

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

May be a web site, an email address, a telephone number, etc.

A free text natural language description of the value set from a consumer's perspective.

& The description is not intended to describe the semantics of the Value Set - there are no intrinsic semantics separate from the codes contained in its expansion. The description should capture its intended use, which is needed for ensuring integrity for its use in models across future changes. A description should be provided unless the value set is a contained resource (e.g. an anonymous value set in a profile). Most registries will require a description.

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 for appropriate value set instances.

Assist in searching for appropriate content.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

A legal or geographic region in which the value set is intended to be used.

It may be possible for the value set to be used in jurisdictions other than those for which it was originally designed or intended.

If this is set to 'true', then no new versions of the content logical definition can be created. Note: Other metadata might still change.

Normally immutability is set to 'false', which is the default assumption if it is not populated. Note that the implication is that if this is set to 'true', there may be only one ValueSet version for this definition. Immutability tends to be set to 'true' in one of two cases: - Where the value set, by the nature of its usage, cannot change. For example "All specializations of ACT in ActClassCode" - Where there's no safe way to express the "Purpose" such that someone else could safely make changes to the value set definition. Source workflow control must guarantee that the same URI always yields the same definition.

Explanation of why this value set is needed and why it has been designed as it has.

This element does not describe the usage of the value set. Instead, it provides traceability of ''why'' the resource is either needed or ''why'' it is defined as it is. This may be used to point to source materials or specifications that drove the structure of this value set.

A copyright statement relating to the value set and/or its contents. Copyright statements are generally legal restrictions on the use and publishing of the value set.

Consumers must be able to determine any legal restrictions on the use of the value set and/or its content.

& Frequently, the copyright differs between the value set and the codes that are included. The copyright statement should clearly differentiate between these when required.

A set of criteria that define the contents of the value set by including or excluding codes selected from the specified code system(s) that the value set draws from. This is also known as the Content Logical Definition (CLD).

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

If a locked date is defined, then the Content Logical Definition must be evaluated using the current version as of the locked date for referenced code system(s) and value set instances where ValueSet.compose.include.version is not defined.

With a defined lockedDate the value set is considered "Locked". Otherwise, the value set may have different expansions as underlying code systems and/or value sets evolve. The interpretation of lockedDate is often dependent on the context - e.g. a SNOMED CT derived value set with a lockedDate will have a different expansion in USA than in UK. If a value set specifies a version for include and exclude statements, and also specifies a locked date, the specified versions need to be available that date, or the value set will not be usable.

Whether inactive codes - codes that are not approved for current use - are in the value set. If inactive = true, inactive codes are to be included in the expansion, if inactive = false, the inactive codes will not be included in the expansion. If absent, the behavior is determined by the implementation, or by the applicable ExpansionProfile (but generally, inactive codes would be expected to be included).

Note that in the FHIR terminology framework, "deprecated" does not mean inactive, but in some code systems (e.g. LOINC, deprecated means inactive). Code systems should define what codes are considered to be inactive. If this is not clearly defined (including in the FHIR code system resource), then all codes are assumed to be active.

Include one or more codes from a code system or other value set(s).

All the conditions in an include must be true. If a system is listed, all the codes from the system are listed. If one or more filters are listed, all of the filters must apply. If one or more value sets are listed, the codes must be in all the value sets. E.g. each include is 'include all the codes that meet all these conditions'.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

An absolute URI which is the code system from which the selected codes come from.

If there are no codes or filters, the entire code system is included. Note that the set of codes that are included may contain abstract codes. See ''Coding.system'' for further documentation about the correct value for the system element.

The version of the code system that the codes are selected from.

This is used when selecting the descendants of a concept - they may change between versions. If no version is specified, then the exact contents of the value set might not be known until a context of use binds it to a particular version.

Specifies a concept to be included or excluded.

The list of concepts is considered ordered, though the order might not have any particular significance. Typically, the order of an expansion follows that defined in the compose element.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Specifies a code for the concept to be included or excluded.

Expressions are allowed if defined by the underlying code system.

The text to display to the user for this concept in the context of this valueset. If no display is provided, then applications using the value set use the display specified for the code by the system.

The value set resource allows for an alternative display to be specified for when this concept is used in this particular value set. See notes in the value set narrative about the correct use of this element.

Additional representations for this concept when used in this value set - other languages, aliases, specialized purposes, used for particular purposes, etc.

Concepts have both a display and an array of designation. The display is equivalent to a special designation with a n implied designation.use of "primary code" and a language equal to the Resource Language.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

The language this designation is defined for.

In the absence of a language, the resource language applies.

A code that details how this designation would be used.

If no use is provided, the designation can be assumed to be suitable for general display to a human user.

The text value for this designation.

Select concepts by specify a matching criteria based on the properties (including relationships) defined by the system. If multiple filters are specified, they SHALL all be true.

Selecting codes by specifying filters based on properties is only possible where the underlying code system defines appropriate properties. Note that in some cases, the underlying code system defines the logical concepts but not the literal codes for the concepts. In such cases, the literal definitions may be provided by a third party.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

A code that identifies a property defined in the code system.

The kind of operation to perform as a part of the filter criteria.

The match value may be either a code defined by the system, or a string value, which is a regex match on the literal string of the property value when the operation is 'regex', or one of the values (true and false), when the operation is 'exists'.

Use regex matching with care - full regex matching on every SNOMED CT term is prohibitive, for example.

Selects the concepts found in this value set (based on its value set definition). This is an absolute URI that is a reference to ValueSet.url. If multiple value sets are specified this includes the union of the contents of all of the referenced value sets.

The value set URI is either a logical reference to a defined value set such as a SNOMED CT reference set, or a direct reference to a value set definition using ValueSet.url. The reference might not refer to an actual FHIR ValueSet resource; in this case, whatever is referred to is an implicit definition of a value set that needs to be clear about how versions are resolved.

Exclude one or more codes from the value set based on code system filters and/or other value sets.

Usually this is used to selectively exclude codes that were included by subsumption in the inclusions. Any display names specified for the codes are ignored.

A value set can also be "expanded", where the value set is turned into a simple collection of enumerated codes. This element holds the expansion, if it has been performed.

Expansion is performed to produce a collection of codes that are ready to use for data entry or validation.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

An identifier that uniquely identifies this expansion of the valueset. Systems may re-use the same identifier as long as the expansion and the definition remain the same, but are not required to do so.

Typically, this uri is a UUID (e.g. urn:uuid:8230ff20-c97a-4167-a59d-dc2cb9df16dd).

The time at which the expansion was produced by the expanding system.

This SHOULD be a fully populated instant, but in some circumstances, value sets are expanded by hand, and the expansion is published without that precision.

The total number of concepts in the expansion. If the number of concept nodes in this resource is less than the stated number, then the server can return more using the offset parameter.

Paging only applies to flat expansions.

If paging is being used, the offset at which this resource starts. I.e. this resource is a partial view into the expansion. If paging is not being used, this element SHALL not be present.

Paging only applies to flat expansions. If a filter is applied, the count is the number of concepts that matched the filter, not the number of concepts in an unfiltered view of the expansion.

A parameter that controlled the expansion process. These parameters may be used by users of expanded value sets to check whether the expansion is suitable for a particular purpose, or to pick the correct expansion.

The server decides which parameters to include here, but at a minimum, the list SHOULD include the date, filter, and profile parameters passed to the $expand operation (if any).

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

The name of the parameter.

The names are assigned at the discretion of the server.

The value of the parameter.

The codes that are contained in the value set expansion.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

An absolute URI which is the code system in which the code for this item in the expansion is defined.

If true, this entry is included in the expansion for navigational purposes, and the user cannot select the code directly as a proper value.

This should not be understood to exclude its use for searching (e.g. by subsumption testing). The client should know whether it is appropriate for the user to select an abstract code or not.

If the concept is inactive in the code system that defines it. Inactive codes are those that are no longer to be used, but are maintained by the code system for understanding legacy data. It might not be known or specified whether an concept is inactive (and it may depend on the context of use).

This should only have a value if the concept is inactive.

The version of this code system that defined this code and/or display. This should only be used with code systems that do not enforce concept permanence.

The exact value of the version string is specified by the system from which the code is derived.

The code for this item in the expansion hierarchy. If this code is missing the entry in the hierarchy is a place holder (abstract) and does not represent a valid code in the value set.

The recommended display for this item in the expansion.

Additional representations for this item - other languages, aliases, specialized purposes, used for particular purposes, etc. These are relevant when the conditions of the expansion do not fix to a single correct representation.

The designations provided must be based on the value set and code system definitions.

Other codes and entries contained under this entry in the hierarchy.

If the expansion uses this element, there is no implication about the logical relationship between them, and the structure cannot be used for logical inferencing. The structure exists to provide navigational assistance for helping human users to locate codes in the expansion.