-- The output port attribute ``abc9_arrival`` specifies an integer, or a string
- of space-separated integers to be used as the arrival time of this blackbox
- port. It can be used, for example, to specify the clk-to-Q delay of a flip-
- flop output for consideration during `abc9` techmapping.
-
-- The input port attribute ``abc9_required`` specifies an integer, or a string
- of space-separated integers to be used as the required time of this blackbox
- port. It can be used, for example, to specify the setup-time of a flip-flop
- input for consideration during `abc9` techmapping.
-