DAL: How It Checks Communication Lines for Errors

Data Access Language does not add error checking on top of the transport data link. That would produce unnecessary overhead. Instead, DAL uses the error checking provided by the transport methods. On asynchronous lines, it can specify parity, databits, stop bits, flow control, packet length, modem timeout, and dial attempts.

For AppleTalk connections, DAL relies on ADSP to handle errors, and for 3270 connections, DAL uses the 3270 display station protocol (LU2) or the APPC (LU6.2) protocol.