3270 terminal screen formats

Unformatted mode

The screen is in unformatted mode:

• When you turn on the display station
• Whenever you press the Clear key on the keyboard

While the screen is in unformatted mode, you can enter the following types of messages:

• IMS commands
• Paging requests (when a message using logical paging is in progress)
• Transaction or message switch data that does not require Message Format Service (MFS)

Formatted mode

IMS MFS defines the 3270 screen to have various fields with predetermined uses. The layout of the fields on the screen and the data displayed depend on the application program. A format consists of all the fields on a screen, and each message sent to a 3270 terminal must indicate a specific format.

An application program might use several types of formats. The format on the screen can change between messages, between input and output sequences of a message, or between transactions.

Different formats define input areas at different locations on the screen. When the 3270 terminal receives a message, the format usually places the 3270 cursor at the beginning of the first input area. The input can consist of commands, transactions, or message switches.

IMS-supplied input formats

Some IMS-supplied formats allow one or two segments of input from the 3270 screen (one segment equals one line on the screen). When you want more than two segments of input, you can use the /FORMAT command to specify the DFSMO4 format. This format is an IMS-supplied format that allows up to four segments of input data. Each segment in the format consists of only the data entered without new line characters or other cursor-control characters.

Installation-defined formats

The installation can develop a variety of formats. Each format definition determines the information that you can enter and the way that you can use the format.

Installation-defined formats allow any of the following (either single-segment or multi-segment):

• Transactions
• Page requests
• Commands

If the current installation-defined format does not allow the necessary input, try using the page-advance function (PA1), the message-advance function (PA2), or the Clear key to produce a screen format that allows entry of the desired data or command. Remember that using PA2 discards the remaining portion of the current output message.