When a new version of SNOMED CT is released this may include changes to the content of the terminology. Components may have been added, inactivated or changed as described in 11.4 Versioning. As part of the terminology maintenance process, it may be appropriate to evaluate both the Representing Reasons for Component Inactivation and to determine appropriate alternatives.
The International Edition of SNOMED CT distributes a set of reference sets that record the reason that each inactive component was inactivated. These are referred to as "historical association" reference sets (see 4.2.3 Historical Association Reference Sets for more details). There is one historical association reference set for each type of historical association as shown in the table below.
Table 220.127.116.11.2-1: Association reference set types in the International Release of SNOMED CT
Association reference set
|(not used currently)|
The following table holds example entries for the 900000000000526001 |Replaced by|reference set. With this reference set is possible to automatically identify that the inactive concept 696005 |Chronobiologic disorder|should be replaced with the concept 387605007 |Abnormal chronobiologic state|. This type of reference set is particularly useful for ensuring consistent use of SNOMED CT over time. The reference set mechanism here provides an easy and standardized way of managing changes to coding or documentation practice over time.
Table 18.104.22.168.2-2: Sample content from 900000000000526001 | REPLACED BY association reference set |
SNOMED RT Concept
SNOMED CT Concept
Salmonella III arizonae 53:k:z
Salmonella IIIb 53:k:z
Special care of patient with contagious disease
Care of patient with infectious disease
Evans and Lloyd-Thomas syndrome
Normal variation in position
Epidural injection of neurolytic substance, lumbar
Epidural injection of neurolytic solution, lumbar
Other disorder of the neurohypophysis, NEC
Disorder of posterior pituitary
Abnormal chronobiologic state
Salmonella III arizonae 50:z4,z23,z32:--
Salmonella IIIa 50:z4,z23,z32:-
Salmonella arizonae 53:z4,z23:--
Salmonella IV 53:z4,z23:--