Specifying input forms for MFS bypass

The two forms of input are:

• MODNAME=DFS.EDT edits the input data.
• MODNAME=DFS.EDTN performs no editing on the input data.

MODNAME=DFS.EDT

The AID and the cursor address are removed from the data stream and any SBA or start field sequences are replaced with blanks. In addition, the basic input edit routine performs the editing. If the AID code received is a CLEAR, PA2, PA3, PFK12, or selector pen attention, existing IMS functions are performed. If a PA1 is received, IMS performs the same function as for PA2 (that is, the next output message is sent if one is available).

MODNAME=DFS.EDTN

If the transaction is in conversational mode, all input is passed to the application as received from the terminal. If the transaction is not in conversational mode, the transaction code must be positioned to precede the AID character of the data stream received from the terminal.

The password should never be passed to the IMS application program. The basic editing functions are performed on the destination and password fields only. If the password appears within parentheses immediately after the transaction code, basic edit removes the password. No editing is performed on the remainder of the data. Existing IMS functions are bypassed for AID codes resulting from a CLEAR, PA1, PA2, PA3, or selector pen attention. PFK12 causes a copy to be performed if it is allowed.

Position the transaction code using the physical terminal input edit exit, or cause IMS to supply it using the conversational or preset destination mode.

If the terminal is in conversational mode, the message is sent to the application program in the conversation. If the terminal is in preset mode, the transaction code is added to the beginning of the message and the message is sent to the destination established by the /SET command. Therefore, while in preset mode, a slash (/) as the first character of the input data is not considered an IMS command. To be recognized as a command, /RESET must immediately follow the cursor address in the input data stream. To do this, enter the /RESET command from an unformatted screen (no fields defined for the screen). If the screen is formatted (fields defined for the screen), press the clear key to unformat the screen. However, an application program must receive the clear AID byte and write a data stream that does not format the screen.

Data stream = F5C3, erases the 3270 buffer.
Data stream = F5C3114040, erases the 3275 buffer.
              Entering: The /RESET command
              resets preset mode.

If /RESET is received from an unformatted screen, while bypassing MFS and basic edit (MOD name is DFS.EDTN) and in preset mode, the input is treated as a command, and the terminal is taken out of preset mode. You are responsible for sending a data stream that leaves the screen unformatted.

If the transaction code and password (if required) are entered with the input message and the terminal is not in conversational or preset mode, your physical terminal input edit exit routine must be included in the IMS system definition. The physical terminal input edit routine gains control before IMS destination and security checking and must modify the input to place the transaction code and password (if required) in front of the AID code.

If the OPTIONS keyword of the IMS system definition TERMINAL or TYPE macro specifies that the keyboard is to remain locked, and the MFS bypass with MOD name DFS.EDTN is used, the application program must assume responsibility for unlocking the 3270 keyboard and resetting the MDT flags.

After use of the MFS bypass, the next output message is formatted by MFS if the MOD name is not supplied or the MOD name supplied is not DFS.EDT or DFS.EDTN.

MFS bypass is intended primarily for subsystems executing under IMS and is not recommended for normal application usage. If IMS application programs deal with 3270 data streams, they become device-dependent, which complicates the application development process.

When a read command is executing in the MFS bypass, the output message containing the read command is dequeued or re-enqueued when the input is received, depending on the option (PAGDEL/NPGDEL) specified on the TERMINAL macro during system definition.