On Field Update Set User Property

How Do You Use the On Field Update Set User Property?
The On Field Update Set user property allows you to set the value of a field in the business component when another field is updated. The parent object type is business component. 



Syntax
The value for On Field Update Set consists of three quoted parameters separated by a comma and a space, as follows:
"[FieldToCheck]", "[FieldToSet]", "[Value]"
[FieldToSet] is set to [Value] when [FieldToCheck] is updated. If the Value parameter is not defined, [FieldToSet] is set to the value of [FieldToCheck].
An expression can optionally be used for the Value parameter. In the following example, the Done field is set using the expression when the Done Flag field is updated:
"Done Flag", "Done", "IIF ([Done Flag] = ""Y"", Today (), """")"
Additionally, if you use an expression, you can include a fourth parameter that defines a condition.

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