7526 DCT Reference
Interactive mode allows the terminal to build a transaction and
lock out any further activity until the transaction is acted on by the
terminal controller, or until a programmable timeout (Timer A in
File 0 record 0, offset 16/17) occurs. The transaction is removed upon
receipt of a CMD B or CMD C from the terminal controller, or when communications
with the terminal controller have timed out.
If timeout occurs, the waiting transaction is cancelled, and an OUT
OF SERVICE message is displayed on the terminal screen. Transactions may
not be entered until the terminal controller resumes polling the terminal.