Current usage:

The purpose of the REPLACED_BY association type is to indicate that the suggested target replacement concept for the inactivated concept is NOT semantically equivalent and therefore represents an alternative which is considered to be clinically useful and in the judgement of the author/editor most closely represents the intended meaning of the inactivated concept. The target concept chosen should be of the same or less specificity than the inactivated concept.

This association type may be used in the following circumstances:

• Where the concept to be inactivated is considered to be "Outdated"
• Where the concept to be inactivated is considered to be "Erroneous"

Proposed changes:

There are a number of additional scenarios in which it would be helpful to provide a potential replacement to the concept being inactivated recognising that the target concept will not be semantically equivalent to the inactivated concept:

• Where a concept has been MOVED_TO a different namespace recognising that while the concept may have been considered to be jurisdictional there is a possibility that it may have been used more widely. Therefore, the inactivation reason of "Component moved elsewhere" would support both MOVED_TO with an optional REPLACED_BY for each inactivated concept.
• Where a concept is considered to be ambiguous but after due diligence the judgement has been made that only one target concept is considered to be appropriate.
• Where a concept is being inactivated due to nonconformance to editorial policy an optional REPLACED_BY should be available.

In each of the above in addition to the use of an optional REPLACED_BY there would be an option to include a note as to why a replacement was considered inappropriate either free text or from a drop down list.

Combinatorial Logic:

Whenever an already stated REPLACED_BY target itself also becomes inactive - whether at the same release or later - the combinatorial logic of associations should be:

(A) REPLACED_BY (B) and (B) SAME_AS (C) implies (A) REPLACED_BY (C)
(A) REPLACED_BY (B) and (B) REPLACED_BY (C) implies (A) REPLACED_BY (C)
(A^IntEd) REPLACED_BY (B^IntEd) and (B^IntEd) MOVED_TO (C^NRC) implies (A^IntEd) MOVED_TO (C^NRC)
(A^IntEd) REPLACED_BY (B^IntEd) and (C^NRC) MOVED_FROM (B^IntEd) implies (A^IntEd) REPLACED_BY (C^NRC)
(A) REPLACED_BY (B) and (B) POSSIBLY_EQUIVALENT_TO (C, D) implies (A) POSSIBLY_EQUIVALENT_TO (C, D)
(A) REPLACED_BY (B) and (B) WAS_A (C AND D) implies (A) WAS_A (C AND D)