Simple Replacement Slots
Replacement slots serve as a placeholder for a value that is not known at the time of authoring, but which can be completed at a subsequent time using data recorded elsewhere (such as in an information model or entered into a data entry form). A slot indicates that it may be replaced by a value by including a plus sign ( + ) as the first symbol within the slot. Replacement slots may be used in an expression template wherever a concept, expression or symbol may appear within an expression.
Focus concept
A replacement slot may be used to delay the selection of a focus concept in an expression. For example, the expression template below uses a slot to indicate that the focus concept in the expression can be replaced with any appropriate SNOMED CT expression. This expression template represents any expression with a single refinement in which the | Laterality| equals | Right| .
If the following values are provided to complete the slot:
182245002 |Entire upper limb| 182281004 |Entire lower limb| 244486005 |Entire eye| 1910005 |Entire ear|
then the expressions that result from processing the template would be:
Attribute Value
A replacement slot may also be used to replace an attribute value in an expression. For example, the expression template below represents any expression with a focus concept of | Clinical finding| and a refinement which uses the attribute | Finding site| . The value of the | Finding site| attribute may be replaced by any valid value at a future time.
If the following value is provided to complete the slot:
53120007 |Upper limb structure|
then the expression that results from processing the template would be:
If, however, the value provided to complete the slot was the expression:
then the result of processing the template would be:
Please note that the template processor must add round brackets around the subexpression to ensure that the resulting expression is syntactically valid.
Attribute Name
A replacement slot may also be used to replace an attribute name in an expression. For example, the expression template below represents any expression with a focus concept of | Clinical finding| and a refinement whose value equals | Rheumatic fever| The attribute name in the expression may be replaced by any valid attribute concept at a future time.
If the following values are provided to complete the slot:
42752001 |Due to| 255234002 |After|
then the expressions that result from processing the template would be:
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