could anyone help regarding a calculation re the above.

what i am try to do is this: i start a standby at 6:00 and i finish it at
18:00 = 12 hrs
but i am called to work at 15:00, so i have completed 8hrs stby. now i can
only count 6 hrs of this sby time towards my total duty time, so i have to
form a what if type of calculation.

start of sby 06:00 fdp allowed 12:15

start of fdp 15:00 total duty allowed 21:15:00

num of setors 2 max finish time 03:15:00

this calulation above is wrong as i can only work until 00:15 so i need to
tell the total duty allowed time cell to minus all time over 6 hrs ( the
differance between the start of sby and start of fdp cells.

thanks for any help