# Logical Record Architecture for Health and Social Care
## Discharge Summary Release 0.02

Contents
The content of this release is not comprehensive and is not fully validated and must not be used in live system implementations.
# Reference Model Class: LINK
The LINK class defines the semantics of a non-containment relationship between two RECORD_COMPONENTs. A source RECORD_COMPONENT may have links to any number of target RECORD_COMPONENTs. Unless further constrained a source RECORD_COMPONENT may contain any number of semantically labelled LINK instances each of which specifies the unique identifier of a target RECORD_COMPONENT. Linking is therefore by reference rather than actual containment. The LRA uses the LINK class to represent predetermined semantic links between RECORD_COMPONENTs at design time (similar in function to the ActRelationship construct used to link Acts in HL7 v3 message models). This is in contrast to arbitrary links between components which are asserted at runtime.using the COMPONENT_RELATIONSHIP_ELEMENT class. ## Attributes
Name | Data type | Occurs | Description
--- | --- | --- | ---
follow_link | BL | 1..1 | If this attribute is TRUE then the COMPOSITION that contains the target RECORD_COMPONENT shall be included in this EHR_EXTRACT.
nature | CS | 1..1 | The general semantic category of the link that is being declared between two RECORD_COMPONENTS. The code set for this attribute is defined in EN 13606-3:2008.
target | II.Uuid.Ref | 1..1 | A set containing the rc_id of each RECORD_COMPONENT that is a target of the link. IN the LRA this set has been constrained to have a size of one. If a specific link is required more than once it must be restated.
## Constraints
Type | Name | Specification
--- | --- | ---
follow_link default value false | Initial value | --Attribute follow_link has default value false. init: follow_link.value.default = false
links allowed only one target in LRA | LRA Invariant | -- SET target has one member inv: target->size() = 1
nature LRA vocab | LRA Inv: Type | inv: nature.code.oclIsTypeOf(<a href="$element://{D98CA40C-B780-4d76-B7A0-54A852557105}"><font color="#0000ff"><u>LraLinkNature</u></font></a>)
target exists | Invariant | --For each and every II instance, i, in SET target there exists within the EHR an instance of a RECORD_COMPONENT specialisation with an rc_id attribute value equal to i inv: target->forAll(i|ehr.record_component->exists(rc_id.equal(i)))
## Reference Model Type ##