SNOMED CT® Release Format 1 (RF1) Guide - ihtsdo

3.2.9.3. relationships tables
Each row in the Relationships Table represents a Relationship between two Concepts.
Note: Most Relationship Types are directional and are therefore regarded as having source concept
and a target concept. Reciprocal relationships are not explicitly represented by rows in the Relationships
Table.
Example: If B is a subtype of A, it follows that A is a supertype of B. The first of these Relationships is
represented by a row in the relationships tables.The reciprocal Relationship is implied and is not restated
by another row in the table
Note:
The Relationship Types supported include the | is a | (subtype) relationship. This is a hierarchical
relationship and only the closest relationships are represented explicitly. Other relationships are subsumed
and are not represented by rows in the Relationships Table.
Example: If C is a subtype of B and B is a subtype of A, it follows that C is a subtype of A. The
Relationship between C and A is not represented by a row in the relationships tables but is subsumed
by the chain of Relationships between C and B and B and A.
Relationships other than | is a | (subtype) relationship are called attribute relationships. These relationships
include the concept (object), relationship type (attribute), and attribute value (another concept). This is
sometimes called the OAV triplet, which stands for Object-Attribute-Value.
Some sets of relationships may have an expected or logical display order (e.g. cranial nerves or cervical
vertebrae). The order is described using the subset mechanism and is not part of the Relationships Table.
In 2003-2004, some relationships were packaged into a separate file called the Historical RelationshipsTable.
These relationships were merged into the Relationships Table starting with the January 2005 release.
To recreate these two tables, use these SQL commands:
Create table historical_relationships as
Select * from relationships
Where characteristic type = "2';
Delete from relationships
Where characteristic type = "2';
Note:
The type of relationship is itself described using a concept.
3.2.9.3.1. Key Fields
Table 81: -
Relationships Table
Key Fields
RelationshipId
Field Type
SCTID
Permitted characters
Digits 0 to 9 only
Release File Formats | 149
Length
6 to 18
The unique SNOMED CT Identifier for this relationship. See Component features - Identifiers (2.1.1.4.2) for
an explanation of the SCTID data type format.
© 2002-2012 International Health Terminology Standards Development Organisation CVR #: 30363434