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SNOMED CT Compositional Grammar may also be used to state the definition of precoordinated concepts. The introduction of definition status to this version of the language makes this usage more feasible. In particular, the definition of a fully defined concept uses an 'equivalent to' definition status to indicate that the expression is necessary and sufficient to define the clinical meaning of the concept. This is the same as giving the concept a definition status of

scg-expression

Concept
t 900000000000073002|Defined|

. The definition of a primitive concept uses a 'subtype of' definition status to indicate that the expression is necessary but not necessarily sufficient to define the clinical meaning of the concept. This is the same as giving the concept a definition status of scg-expression

Concept
t 900000000000074008|Primitive|

.

For example,

scg-expression

Concept
t 31978002|Fracture

of

tibia|

(a fully defined precoordinated concept) can be defined using a compositional grammar expression as being 'equivalent to' an scg-expression

Concept

ShowParts

t

term

428881005|Injury

of

tibia|

 and a

Scg expression

Concept
t

ShowPartsterm

46866001|Fracture

of

lower

limb|

, with an term

Scg expression
ShowParts

Concept
t 116676008|Associated

morphology|

 of scg-expression

Concept

ShowParts

t

term

72704001|Fracture|

 and a term

Scg expression
ShowParts

Concept
t 363698007|Finding

site|

 of scg-expression

Concept

ShowParts

t

term

12611008|Bone

structure

of

tibia|

. This definition is shown below in Figure 1 using the SNOMED CT Diagramming Guidelines.

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