The goal is to count the number of days that an Employee is not assigned work within a given month (MONTH A, MONTH B, etc).
For example, a given month has 23 working days; I could use NETWORKDAYS of the duration to count the assigned days of that Task; say 19. To reach my goal, I would simply subract the NETWORKDAYS from the number of workdays within that month: 23-19=4 days.
But... if the duration spans across 2 months, how can I return the NETWORKDAYS of this duration for just MONTH A? In the above example, 6 days are in MONTH A, and 13 days are in MONTH B.