Linkage concept

This hierarchy includes concepts used for linkage. 

The Linkage concept hierarchy contains the sub-hierarchies: 

• Link assertion
• Attribute 

The Link assertion sub-hierarchy enables the use of SNOMED CT concepts in HL7 statements that assert relationships between statements. Currently this content supports the UK NHS Connecting for Health requirements for encoding of Statement relationships for the implementation of HL7 Version 3 messaging in the UK realm. 

Examples of Link assertion concepts: 

• Has reason (link assertion)
• Has explanation (link assertion) 

Concepts that descend from this sub-hierarchy are used to construct relationships between two SNOMED CT concepts, since they indicate the relationship type between those concepts. Some attributes (relationship types) can be used to logically define a concept (defining attributes). This sub-hierarchy also includes non-defining attributes (like those used to track historical relationships between concepts) or attributes that may be useful to model concept definitions but which have not yet been used in modeling pre-coordinated concepts in SNOMED CT. 

•  IS_A (attribute)
• Concept model attribute (attribute): 
  • Laterality (attribute)
  • Procedure site (attribute)
  • Finding site (attribute)
  • Associated morphology (attribute) 

Examples of Non-defining attributes: 

• Concept history attribute (attribute) 
  • REPLACED BY (attribute)
  • SAME AS (attribute)
• Unapproved attribute (attribute) 
  • Relieved by (attribute)
  • Has assessment (attribute)