Stepping up its challenge for the emerging international electronic data interchange market, IBM yesterday announced that from May 1 users of its Information Network in the US and in 12 European countries will be able to exchange data with trading partners interactively. IBM sees the service being used for electronic mail, orders, invoices and shipping notices, and access to on-line databases and applications. Up to now, IBM offered only store-and-forward messages and batch data transfer; X25 public network access is supported in 40 other countries.