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Calculations are calculated when their value is requested, for example when it is displayed in the UI or used in scripting or in another calculation and the value was not calculated yet or has been flagged as invalid. A calculation is flagged as invalidated when a change occurs in one of the dataproviders on which the calculation depends.

When the returned value of a calculation changes, all elements in the UI If there are UI elements that display the calculation value will be automatically updated, they will be notified to update themselves and the calculation is executed to calculate the new value. 

If the calculation is a stored calculation, the record it is part of will be marked as changed (thus it'll be in the list of edited records) and will be part of next save action.

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