Project management Glossary of Terms - Actual Work
Actual Work – working time actually performed by resources assigned to tasks.
Actual work occurs when a task is partially or completely done. It is calculated from its total work and completion level as follows:
      Actual Work = Work * %Work Complete
Consequently if a task has no work associated (this happens for example if there are no resources assigned), the Actual Work value cannot be set to a value other than zero. In any other conditions, specifying a value for Actual Work will set automatically a corresponding value for % Work Complete (and Remaining Work) and vice versa.