Unformatted mode

Even though the high function of the 3270 revolves around its field structure, it is possible to use the 3270 without fields, in what is called unformatted mode. In this mode, there are no fields defined, and the entire screen (buffer) behaves as a single string of data, inbound and outbound, much like earlier, simpler terminals.

When you write in unformatted mode, you define no fields in your data, although you can include SBA orders to direct the data to a particular positions on the screen. Data that precedes any SBA order is written starting at the current position of the cursor. (If you use an erase or write command, the cursor is automatically set to zero, at the upper left corner of the screen.)

When you read an unformatted screen, the first three bytes are the read header (the AID and the cursor address), just as when you read a formatted screen. The remaining bytes are the contents of the entire buffer, starting at position zero. There are no SBA or SF orders present, because there are no fields. If the read command was read modified, the nulls are suppressed, and therefore it is not always possible to determine exactly where on the screen the input data was located.

You cannot use a BMS RECEIVE MAP command to read an unformatted screen. BMS raises the MAPFAIL condition on detecting unformatted input, as explained in MAPFAIL and other exceptional conditions. You can read unformatted data only with a terminal control RECEIVE command in CICS®.

Note:
The CLEAR key puts the screen into unformatted mode, because its sets the buffer to nulls, thereby erasing all the attributes bytes that demarcate fields.
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