In some cases, you have to reset the parity because the system that you are calling checks port parity and drops the line if it is wrong. The expect-send couplet "" P_ZERO sets the high-order bit (parity bit) to 0. For example:
unix Any ACU 2400 12015551212 "" P_ZERO "" \r login:-\r-login:-\r-login: nuucp password: xxx
In the same manner, P_EVEN sets parity to even (the default), P_ODD sets odd parity, and P_ONE sets the parity bit to 1.