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One scenario in which the first form-based approach may be used is when there is a terminology-based dependency between the values of two fields on a user interface. For example, Figure 4 illustrates a simplified Procedures form in which the coded value entered into the Procedure Type field must be a descendant of the coded value entered into the Procedure Category field. When a Procedure Category of "Surgery" (i.e.
scg-expression ) is selected, the expression constraint "
scg-expression " is used to populate the value list for the
Procedure Type field.
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