A SNOMED CT Compositional Grammar expression begins with an optional definition status,
contains one or more focus concepts (represented by a concept identifier) and optionally
has a refinement. Each refinement may contain grouped or ungrouped attributes (or
both). An attribute
1
consists of the attribute name (represented by a concept identifier) together with
the value of the attribute. The attribute value is either an expression or a concrete
value (string, integer or decimal). Figure 2 below illustrates the overall structure
of a compositional grammar expression using an abstract representation. Please note
that no specific semantics should be attributed to each arrow in this abstract diagram.
Figure 2: Abstract Model of a Compositional Grammar expression
Figure 3 below shows an example of an expression with the main components marked.
These components will be explained further in the subsequent sections of this document.
Figure 3: The main parts of an example expression
| Ref | Notes |
|---|---|
| 1 |
Please note that, in the context of an expression, the word 'Attribute' is used to refer to the name/value pair within a refinement. However, in the context of the SNOMED CT concept model, the word 'Attribute' is often used to refer specifically to the 'attribute name' (i.e. the concept used as the relationship type). |
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