---
type: "resource-definitions"
title: "MessageHeader Definitions"
resource: "MessageHeader"
---

# MessageHeader Definitions

<a id="MessageHeader"></a>

## MessageHeader
A resource that describes a message that is exchanged between systems

**Definition:** The header for a message exchange that is either requesting or responding to an action.  The reference(s) that are the subject of the action as well as other information related to the action are typically transmitted in a bundle in which the MessageHeader resource instance is the first resource in the bundle.

**Cardinality:** 0..*

**Mappings:** workflow=Event; v2=MSH / MSA / ERR; rim=Message; w5=infrastructure.exchange


<a id="MessageHeader.event[x]"></a>

## MessageHeader.event[x]
The real world event that triggered this messsage

**Definition:** Code that identifies the event this message represents and connects it with its definition. Events are defined by codes, or by URIs that identify events, or by reference to EventDefinition or SubscriptionTopic resources that define the event directly. This element is intentionally unbound, and the selection of appropriate event codes is delegated to implementations and implementation guides. For codes, a good set of example codes is found in [the V2 event codes](https://terminology.hl7.org/ValueSet-v2-0003.html).

**Comments:** The time of the event will be found in the focus resource. The time of the message will be found in [Bundle.timestamp](bundle-definitions.html#Bundle.timestamp).

**Requirements:** Drives the behavior associated with this message.

**Cardinality:** 1..1

**Type:** [Coding](/Coding), [uri](/uri), [canonical](/canonical)

**Binding:** example:[message-events](/valueset-message-events)

**Summary:** true

**Mappings:** workflow=Event.code; w5=FiveWs.what[x]; v2=MSH-9.2; rim=./payload[classCode="CACT" and moodCode="EVN" and isNormalAct()]/code[isNormalDatatype()]/code


<a id="MessageHeader.destination"></a>

## MessageHeader.destination
Message destination application(s)

**Definition:** The destination application which the message is intended for.

**Comments:** There SHOULD be at least one destination, but in some circumstances, the source system is unaware of any particular destination system.

**Requirements:** Indicates where message is to be sent for routing purposes.  Allows verification of "am I the intended recipient".

**Cardinality:** 0..*

**Type:** [BackboneElement](/BackboneElement)

**Summary:** true

**Mappings:** w5=FiveWs.subject; rim=./communicationFunction[typeCode="RCV"]


<a id="MessageHeader.destination.endpoint[x]"></a>

## MessageHeader.destination.endpoint[x]
Actual destination address or Endpoint resource

**Definition:** Indicates where the message should be routed.

**Comments:** The url may be a non-resolvable URI for systems that do not use standard network-based addresses.

**Requirements:** Identifies where to route the message.

**Cardinality:** 0..1

**Type:** [url](/url), Reference([Endpoint](/Endpoint))

**Summary:** true


<a id="MessageHeader.destination.name"></a>

## MessageHeader.destination.name
Name of system

**Definition:** Human-readable name for the target system.

**Requirements:** May be used for routing of response and/or to support audit.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** v2=MSH-5; rim=unique(./entity[determinerCode="INST" and (classCode=("DEV", "PSN", "ORG"]/name[type='ST' and isNormalDatatype()])


<a id="MessageHeader.destination.receiver"></a>

## MessageHeader.destination.receiver
Intended "real-world" recipient for the data

**Definition:** Allows data conveyed by a message to be addressed to a particular person or department when routing to a specific application isn't sufficient.

**Requirements:** Allows routing beyond just the application level.

**Cardinality:** 0..1

**Type:** Reference([Device](/Device), [Organization](/Organization), [Patient](/Patient), [Practitioner](/Practitioner), [PractitionerRole](/PractitionerRole), [RelatedPerson](/RelatedPerson))

**Summary:** true

**Mappings:** w5=FiveWs.subject; v2=PRT-5:PRT-4='WAYR' / PRT-8:PRT-4='WAYR'; rim=Not directly supported.  Could be shared using attentionLine.value with an appropriate keyWordText


<a id="MessageHeader.source"></a>

## MessageHeader.source
Message source application

**Definition:** The source application from which this message originated.

**Requirements:** Allows replies, supports audit.

**Cardinality:** 1..1

**Type:** [BackboneElement](/BackboneElement)

**Summary:** true

**Mappings:** w5=FiveWs.actor; rim=unique(./communicationFunction[typeCode="SND"])


<a id="MessageHeader.source.endpoint[x]"></a>

## MessageHeader.source.endpoint[x]
Actual source address or Endpoint resource

**Definition:** Identifies the routing target to send acknowledgements to.

**Comments:** The url may be a non-resolvable URI for systems that do not use standard network-based addresses.

**Requirements:** Identifies where to send responses, may influence security permissions.

**Cardinality:** 0..1

**Type:** [url](/url), Reference([Endpoint](/Endpoint))

**Summary:** true


<a id="MessageHeader.source.name"></a>

## MessageHeader.source.name
Name of system

**Definition:** Human-readable name for the source system.

**Requirements:** May be used to support audit.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** v2=MSH-3; rim=unique(./entity[determinerCode="INST" and classCode="DEV"]/name[type='ST' and isNormalDatatype()])


<a id="MessageHeader.source.software"></a>

## MessageHeader.source.software
Name of software running the system

**Definition:** May include configuration or other information useful in debugging.

**Requirements:** Supports audit and possibly interface engine behavior.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** v2=SFT-3 ( +SFT-1); rim=unique(./entity[determinerCode="INST" and classCode="DEV"]/softwareName[isNormalDatatype()])


<a id="MessageHeader.source.version"></a>

## MessageHeader.source.version
Version of software running

**Definition:** Can convey versions of multiple systems in situations where a message passes through multiple hands.

**Requirements:** Supports audit and possibly interface engine behavior.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** v2=SFT-2; rim=(Not supported)


<a id="MessageHeader.source.contact"></a>

## MessageHeader.source.contact
Human contact for problems

**Definition:** An e-mail, phone, website or other contact point to use to resolve issues with message communications.

**Requirements:** Allows escalation of technical issues.

**Cardinality:** 0..1

**Type:** [ContactPoint](/ContactPoint)

**Summary:** true

**Mappings:** v2=(MSH-22?); rim=unique(./entity[determinerCode="INST" and classCode="DEV"]/scopesRole[normalRole() and classCode="CON" and layer[classCode="PSN"]/telecom[isNormalDatatype()])


<a id="MessageHeader.source.sender"></a>

## MessageHeader.source.sender
Real world sender of the message

**Definition:** Identifies the sending entity to allow the use of a trust relationship.

**Comments:** Use case is for where a (trusted) sending system is responsible for multiple organizations, and therefore cannot differentiate based on source endpoint / authentication alone. Proposing to remove and rely on Task to convey this information.

**Requirements:** Allows routing beyond just the application level.

**Cardinality:** 0..1

**Type:** Reference([Device](/Device), [Organization](/Organization), [Patient](/Patient), [Practitioner](/Practitioner), [PractitionerRole](/PractitionerRole))

**Summary:** true


<a id="MessageHeader.reason"></a>

## MessageHeader.reason
Cause of event

**Definition:** Coded indication of the cause for the event - indicates  a reason for the occurrence of the event that is a focus of this message.

**Requirements:** Need to be able to track why resources are being changed and report in the audit log/history of the resource.  May affect authorization.

**Cardinality:** 0..1

**Type:** [CodeableConcept](/CodeableConcept)

**Binding:** example:[message-reason-encounter](/valueset-message-reason-encounter)

**Summary:** true

**Mappings:** w5=FiveWs.why[x]; workflow=Event.reason; v2=EVN-4 / ORC-16 / OBR-31 / BPO-13 / RXO-20 / RXE-27 / RXD-21 / RXG-22 / RXA-19; rim=unique(./controlAct[classCode="CACT" and classCode="EVN" and isNormalAct()]/reasonCode[isNormalDatatype()])


<a id="MessageHeader.response"></a>

## MessageHeader.response
If this is a reply to prior message

**Definition:** Information about the message that this message is a response to.  Only present if this message is a response.

**Cardinality:** 0..1

**Type:** [BackboneElement](/BackboneElement)

**Summary:** true

**Mappings:** v2=MSA; rim=./conveyedAcknowledgement


<a id="MessageHeader.response.identifier"></a>

## MessageHeader.response.identifier
Bundle.identifier of original message

**Definition:** The Bundle.identifier of the message to which this message is a response.

**Requirements:** Allows receiver to know what message is being responded to.

**Cardinality:** 1..1

**Type:** [Identifier](/Identifier)

**Summary:** true

**Mappings:** v2=MSA-2; rim=./acknowledges.id[isNormalDatatype()]


<a id="MessageHeader.response.code"></a>

## MessageHeader.response.code
ok | transient-error | fatal-error

**Definition:** Code that identifies the type of response to the message - whether it was successful or not, and whether it should be resent or not.

**Comments:** This is a generic response to the request message. Specific data for the response will be found in MessageHeader.focus.

**Requirements:** Allows the sender of the acknowledge message to know if the request was successful or if action is needed.

**Cardinality:** 1..1

**Type:** [code](/code)

**Binding:** required:[response-code](/valueset-response-code)

**Summary:** true

**Mappings:** v2=MSA-1; rim=./typeCode[isNormalDatatype()]


<a id="MessageHeader.response.details"></a>

## MessageHeader.response.details
Specific list of hints/warnings/errors

**Definition:** Full details of any issues found in the message.

**Comments:** This SHALL be contained in the bundle. If any of the issues are errors, the response code SHALL be an error.

**Requirements:** Allows the sender of the message to determine what the specific issues are.

**Cardinality:** 0..1

**Type:** Reference([OperationOutcome](/OperationOutcome))

**Summary:** true

**Mappings:** v2=ERR; rim=AcknowledgementDetail or Observation[classCode="ALRT" and moodCode="EVN"]


<a id="MessageHeader.focus"></a>

## MessageHeader.focus
The actual content of the message

**Definition:** The actual data of the message - a reference to the root/focus class of the event. This is allowed to be a Parameters resource.

**Comments:** The data is defined where the transaction type is defined. The transaction data is always included in the bundle that is the full message.  Only the root resource is specified.  The resources it references should be contained in the bundle but are not also listed here.  Multiple repetitions are allowed to cater for merges and other situations with multiple focal targets.

**Requirements:** Every message event is about actual data, a single resource, that is identified in the definition of the event, and perhaps some or all linked resources.

**Cardinality:** 0..*

**Type:** Reference([Resource](/Resource))

**Summary:** true

**Mappings:** rim=unique(./controlAct[classCode="CACT" and classCode="EVN" and isNormalAct()]/participation[typeCode="SUBJ" and isNormalParticipation]/role or ./controlAct[classCode="CACT" and classCode="EVN" and isNormalAct()]/outboundRelationship[typeCode="SBJ" and isNormalActRelatoinship]/target)


<a id="MessageHeader.definition"></a>

## MessageHeader.definition
Link to the definition for this message

**Definition:** Permanent link to the MessageDefinition for this message.

**Requirements:** Allows sender to define the expected contents of the message.

**Cardinality:** 0..1

**Type:** [canonical](/canonical)

**Summary:** true

**Mappings:** rim=Not directly supported.