Quotron’s customers reacted coolly to a bid.

Quotron Systems Chairman Milton E. Mohr said several customers and joint-venture partners, including AT&T;, have voiced concerns about Citicorp gaining access to their confidential business plans if the banking firm acquires Quotron. Mohr said, however, that he doesn’t know if any customers will withdraw their business if Citicorp’s $680-million bid succeeds.