A list is a curated collection of resources.

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.

The version specific identifier, as it appears in the version portion of the URL. This value changes when the resource is created, updated, or deleted.

The server assigns this value, and ignores what the client specifies, except in the case that the server is imposing version integrity on updates/deletes.

When the resource last changed - e.g. when the version changed.

This value is always populated except when the resource is first being created. The server / resource manager sets this value; what a client provides is irrelevant. This is equivalent to the HTTP Last-Modified and SHOULD have the same value on a read interaction.

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.

Expresses contentType of submissionSet or the codeList of a Folder. Usually expressed in LOINC or SNOMED.

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.

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Kategorie des Folder, die die Art der Dokumente im Folder näher beschreibt und einem Wert aus dem ValueSet 'EPA Data Category (Other)' entspricht.

Die Kategorie wird durch den Server gesetzt.

The globally unique, immutable, identifier of the homeCommunityId entity where this artifact resides. The format of the value is an OID.

An Extension

Identifier for the List assigned for business purposes outside the context of FHIR.

Der eindeutige aktenweit eindeutige Identifikator des Folder, der dem Element Folder.uniqueId in XDS entspricht.

Beim Einstellen eines Folder wird dieser Wert vom Service generiert. Beim Lesen ist dieser Wert immer gesetzt.

Der intern verwendete, aktenweit eindeutige Identifikator des Folder, der dem Element Folder.entryUUID in XDS entspricht.

Beim Einstellen eines Folder wird dieser Wert vom Service generiert. Beim Lesen ist dieser Wert immer gesetzt.

Status für den Folder, der dem Element Folder.availabilityStatus in XDS entspricht.

n/a

The current state of the list.

Verarbeitungsmodus des Folder

n/a

The processing mode that applies to this list.

Lists are used in various ways, and it must be known in what way it is safe to use them.

Code für die Kennzeichnung dieser Liste als Folder

Dieser Code gibt die Art der Liste an, hier 'folder', ein Folder, der Dokumente enthält.

Lists often contain subsets of resources rather than an exhaustive list. The code identifies what type of subset is included.

A reference to a code defined by a terminology system.

Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.

Allows for alternative encodings within a code system, and translations to other code systems.

The common subject (or patient) of the resources that are in the list if there is one.

Some purely arbitrary lists do not have a common subject, so this is optional.

The primary purpose of listing the subject explicitly is to help with finding the right list.

The encounter that is the context in which this list was created.

Erstellungszeitpunkt des SubmissionSet

Dieser Zeitpunkt wird vom Service gesetzt.

Identifies how current the list is which affects relevance.

The entity responsible for deciding what the contents of the list were. Where the list was created by a human, this is the same as the author of the list.

The primary source is the entity that made the decisions what items are in the list. This may be software or user.

Allows follow-up as well as context.

What order applies to the items in the list.

Applications SHOULD render ordered lists in the order provided, but MAY allow users to re-order based on their own preferences as well. If there is no order specified, the order is unknown, though there may still be some order.

What order applies to the items in a list.

Important for presentation and rendering. Lists may be sorted to place more important information first or to group related entries.

Comments that apply to the overall list.

Entries in this list.

If there are no entries in the list, an emptyReason SHOULD be provided.

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 and/or the understanding of the containing element's descendants. 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.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

The flag allows the system constructing the list to indicate the role and significance of the item in the list.

The flag can only be understood in the context of the List.code. If the flag means that the entry has actually been deleted from the list, the deleted element SHALL be true. Deleted can only be used if the List.mode is "changes".

Codes that provide further information about the reason and meaning of the item in the list.

This field is present to support various clinical uses of lists, such as a discharge summary medication list, where flags specify whether the medication was added, modified, or deleted from the list.

True if this item is marked as deleted in the list.

If the flag means that the entry has actually been deleted from the list, the deleted element SHALL be true. Both flag and deleted can only be used if the List.mode is "changes". A deleted entry should be displayed in narrative as deleted. This element is labeled as a modifier because it indicates that an item is (to be) no longer in the list.

The flag element may contain codes that an application processing the list does not understand. However there can be no ambiguity if a list item is actually marked as "deleted".

When this item was added to the list.

The date may be significant for understanding the meaning of items in a working list.

Referenz auf die Dokumente im Folder, welche dem Element Folder.entry.item in XDS entspricht.

Logical Reference unter Nutzung der entryUUID

An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.

When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference

Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.

Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

If the list is empty, why the list is empty.

The various reasons for an empty list make a significant interpretation to its interpretation. Note that this code is for use when the entire list has been suppressed, and not for when individual items are omitted - implementers may consider using a text note or a flag on an entry in these cases.

If a list is empty, why it is empty.

Allows capturing things like "none exist" or "not asked" which can be important for most lists.

Kategorie des Folder, die die Art der Dokumente im Folder näher beschreibt und einem Wert aus dem ValueSet 'EPA Data Category (Other)' entspricht.

Die Kategorie wird durch den Server gesetzt.

Der eindeutige aktenweit eindeutige Identifikator des Folder, der dem Element Folder.uniqueId in XDS entspricht.

Beim Einstellen eines Folder wird dieser Wert vom Service generiert. Beim Lesen ist dieser Wert immer gesetzt.

Der intern verwendete, aktenweit eindeutige Identifikator des Folder, der dem Element Folder.entryUUID in XDS entspricht.

Beim Einstellen eines Folder wird dieser Wert vom Service generiert. Beim Lesen ist dieser Wert immer gesetzt.

Status für den Folder, der dem Element Folder.availabilityStatus in XDS entspricht.

n/a

Verarbeitungsmodus des Folder

n/a

Code für die Kennzeichnung dieser Liste als Folder

Dieser Code gibt die Art der Liste an, hier 'folder', ein Folder, der Dokumente enthält.

Erstellungszeitpunkt des SubmissionSet

Dieser Zeitpunkt wird vom Service gesetzt.

Referenz auf die Dokumente im Folder, welche dem Element Folder.entry.item in XDS entspricht.

Logical Reference unter Nutzung der entryUUID

A list is a curated collection of resources.

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.

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.

The version specific identifier, as it appears in the version portion of the URL. This value changes when the resource is created, updated, or deleted.

The server assigns this value, and ignores what the client specifies, except in the case that the server is imposing version integrity on updates/deletes.

When the resource last changed - e.g. when the version changed.

This value is always populated except when the resource is first being created. The server / resource manager sets this value; what a client provides is irrelevant. This is equivalent to the HTTP Last-Modified and SHOULD have the same value on a read interaction.

A uri that identifies the source system of the resource. This provides a minimal amount of Provenance information that can be used to track or differentiate the source of information in the resource. The source may identify another FHIR server, document, message, database, etc.

In the provenance resource, this corresponds to Provenance.entity.what[x]. The exact use of the source (and the implied Provenance.entity.role) is left to implementer discretion. Only one nominated source is allowed; for additional provenance details, a full Provenance resource should be used.

This element can be used to indicate where the current master source of a resource that has a canonical URL if the resource is no longer hosted at the canonical URL.

A list of profiles (references to StructureDefinition resources) that this resource claims to conform to. The URL is a reference to StructureDefinition.url.

It is up to the server and/or other infrastructure of policy to determine whether/how these claims are verified and/or updated over time. The list of profile URLs is a set.

Security labels applied to this resource. These tags connect specific resources to the overall security policy and infrastructure.

The security labels can be updated without changing the stated version of the resource. The list of security labels is a set. Uniqueness is based the system/code, and version and display are ignored.

Security Labels from the Healthcare Privacy and Security Classification System.

Tags applied to this resource. Tags are intended to be used to identify and relate resources to process and workflow, and applications are not required to consider the tags when interpreting the meaning of a resource.

The tags can be updated without changing the stated version of the resource. The list of tags is a set. Uniqueness is based the system/code, and version and display are ignored.

Codes that represent various types of tags, commonly workflow-related; e.g. "Needs review by Dr. Jones".

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 language.

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.

An Extension

Expresses contentType of submissionSet or the codeList of a Folder. Usually expressed in LOINC or SNOMED.

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.

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Kategorie des Folder, die die Art der Dokumente im Folder näher beschreibt und einem Wert aus dem ValueSet 'EPA Data Category (Other)' entspricht.

Die Kategorie wird durch den Server gesetzt.

The globally unique, immutable, identifier of the homeCommunityId entity where this artifact resides. The format of the value is an OID.

An Extension

Identifier for the List assigned for business purposes outside the context of FHIR.

Der eindeutige aktenweit eindeutige Identifikator des Folder, der dem Element Folder.uniqueId in XDS entspricht.

Beim Einstellen eines Folder wird dieser Wert vom Service generiert. Beim Lesen ist dieser Wert immer gesetzt.

Der intern verwendete, aktenweit eindeutige Identifikator des Folder, der dem Element Folder.entryUUID in XDS entspricht.

Beim Einstellen eines Folder wird dieser Wert vom Service generiert. Beim Lesen ist dieser Wert immer gesetzt.

Status für den Folder, der dem Element Folder.availabilityStatus in XDS entspricht.

n/a

The current state of the list.

Verarbeitungsmodus des Folder

n/a

The processing mode that applies to this list.

Lists are used in various ways, and it must be known in what way it is safe to use them.

A label for the list assigned by the author.

Allows customization beyond just the code identifying the kind of list.

Code für die Kennzeichnung dieser Liste als Folder

Dieser Code gibt die Art der Liste an, hier 'folder', ein Folder, der Dokumente enthält.

Lists often contain subsets of resources rather than an exhaustive list. The code identifies what type of subset is included.

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.

A reference to a code defined by a terminology system.

Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.

Allows for alternative encodings within a code system, and translations to other code systems.

A human language representation of the concept as seen/selected/uttered by the user who entered the data and/or which represents the intended meaning of the user.

Very often the text is the same as a displayName of one of the codings.

The codes from the terminologies do not always capture the correct meaning with all the nuances of the human using them, or sometimes there is no appropriate code at all. In these cases, the text is used to capture the full meaning of the source.

The common subject (or patient) of the resources that are in the list if there is one.

Some purely arbitrary lists do not have a common subject, so this is optional.

The primary purpose of listing the subject explicitly is to help with finding the right list.

The encounter that is the context in which this list was created.

Erstellungszeitpunkt des SubmissionSet

Dieser Zeitpunkt wird vom Service gesetzt.

Identifies how current the list is which affects relevance.

The entity responsible for deciding what the contents of the list were. Where the list was created by a human, this is the same as the author of the list.

The primary source is the entity that made the decisions what items are in the list. This may be software or user.

Allows follow-up as well as context.

What order applies to the items in the list.

Applications SHOULD render ordered lists in the order provided, but MAY allow users to re-order based on their own preferences as well. If there is no order specified, the order is unknown, though there may still be some order.

What order applies to the items in a list.

Important for presentation and rendering. Lists may be sorted to place more important information first or to group related entries.

Comments that apply to the overall list.

Entries in this list.

If there are no entries in the list, an emptyReason SHOULD be provided.

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 and/or the understanding of the containing element's descendants. 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.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

The flag allows the system constructing the list to indicate the role and significance of the item in the list.

The flag can only be understood in the context of the List.code. If the flag means that the entry has actually been deleted from the list, the deleted element SHALL be true. Deleted can only be used if the List.mode is "changes".

Codes that provide further information about the reason and meaning of the item in the list.

This field is present to support various clinical uses of lists, such as a discharge summary medication list, where flags specify whether the medication was added, modified, or deleted from the list.

True if this item is marked as deleted in the list.

If the flag means that the entry has actually been deleted from the list, the deleted element SHALL be true. Both flag and deleted can only be used if the List.mode is "changes". A deleted entry should be displayed in narrative as deleted. This element is labeled as a modifier because it indicates that an item is (to be) no longer in the list.

The flag element may contain codes that an application processing the list does not understand. However there can be no ambiguity if a list item is actually marked as "deleted".

When this item was added to the list.

The date may be significant for understanding the meaning of items in a working list.

Referenz auf die Dokumente im Folder, welche dem Element Folder.entry.item in XDS entspricht.

Logical Reference unter Nutzung der entryUUID

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.

A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.

Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.

The expected type of the target of the reference. If both Reference.type and Reference.reference are populated and Reference.reference is a FHIR URL, both SHALL be consistent.

The type is the Canonical URL of Resource Definition that is the type this reference refers to. References are URLs that are relative to http://hl7.org/fhir/StructureDefinition/ e.g. "Patient" is a reference to http://hl7.org/fhir/StructureDefinition/Patient. Absolute URLs are only allowed for logical models (and can only be used in references in logical models, not resources).

This element is used to indicate the type of the target of the reference. This may be used which ever of the other elements are populated (or not). In some cases, the type of the target may be determined by inspection of the reference (e.g. a RESTful URL) or by resolving the target of the reference; if both the type and a reference is provided, the reference SHALL resolve to a resource of the same type as that specified.

Aa resource (or, for logical models, the URI of the logical model).

An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.

When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference

Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.

Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

Plain text narrative that identifies the resource in addition to the resource reference.

This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.

If the list is empty, why the list is empty.

The various reasons for an empty list make a significant interpretation to its interpretation. Note that this code is for use when the entire list has been suppressed, and not for when individual items are omitted - implementers may consider using a text note or a flag on an entry in these cases.

If a list is empty, why it is empty.

Allows capturing things like "none exist" or "not asked" which can be important for most lists.