3.3 Expression Relation Diagrams

The diagramming notation described in this document can also be used to describe the relationship between two different SNOMED CT expressions.

This is represented by two expression diagrams, one above the other, separated by a relational operator between. The diagram is read top to bottom.

As an example below is a diagram showing two expressions that are equivalent:

Note that in this example the equivalence relation connects the two expressions with lines – indicating that the relationship is bidirectional and can be read either way.