I wrote gantt chart as follows:
saturday are closed
sunday are closed
project starts the 2023-7-1
[A] starts at 2023-7-1 and lasts 3 days
[B] starts 10 working days after [A]'s end
[B2] starts 10 days after [A]'s end
[C] starts at 2023-7-1 and ends 10 working days before [B]'s start
[C2] starts at 2023-7-1 and ends 10 days before [B]'s start
The satart days of [B] and [B2] become different.
"working days after" looks like working correctly.
On the other hand, the end days of C and C2 became same.
"working days before" works as same as "days before" ?