Table completeness: NoVal should not be considered as an option value of the input.
When do the Completeness analysis on function tables, NoVal will be
considered as an option value of the input.
In so doing, even when the input conditions are complete, a missing
condition will be found, and (input == NoVal) will be token as an
evidence of the analysis result.
(from redmine: issue id 1997, created on 2014-04-02, closed on 2014-07-22)