- The port attribute ``abc_carry`` marks the carry-in (if an input port) and
carry-out (if output port) ports of a box. This information is necessary for
`abc9` to preserve the integrity of carry-chains. Specifying this attribute
- onto a bus port will affect its most significant bit.
+ onto a bus port will affect only its most significant bit.
Non-standard or SystemVerilog features for formal verification