Property :: execute - Execute Handle
When a property handle has been opened for an operation, the function can be called in order to calculate the result of the operation.
When an operation has been defined relatively to another property, the operation has to be recalculated each time when the parent property handle (calling object) changes the selection.
For property handles not referring to OSI expressions, the function does not have any effect.
Notes:
Transient references or attributes based on source expressions are, usually, calculated automatically, whenever necessary. In order to force recalculation of transient fields, one may also call execute().