Format library member selection

Recommendation: You should define device formats for each device type expected to receive a given message. If the MOD or the DOF with the required device type and feature specification cannot be located during online execution, the IMS error default format (containing an error message) is used to display the output message. If the MID or the DIF with the required device type and feature specification cannot be located, input is ignored and an error message is sent to the device that entered it.

However, it is possible to use the same format for a variety of specific devices. Formats defined as TYPE=3270,2 with FEAT=IGNORE specified, can be used as default formats for users of the following devices:

• 3275
• 3276, models 2/3/4
• 3277, model 2
• 3278, models 2/3/4
• 3279, models 2/3

To define the terminal to IMS, you must specify TYPE=3270-An with SIZE=(n,80), where n≥24.

The terminal must be defined to IMS as TYPE=3270,2 or MFS searches for a block with the exact TYPE and FEAT specification, and if one is not found, MFS searches for the default TYPE=3270,2 with FEAT=IGNORE.

Another level of defaulting occurs for ETO terminals prior to the already described defaulting. If an ETO terminal is defined with a screen size of 12x40 or 24x80 in the VTAM® PSERVIC information, and that format block is not found, an additional search is made for a format of the same name using TYPE=3270,1 (12x40) or TYPE=3270,2 (24x80) and using the same features. If that search is unsuccessful, the already described default search is performed. This new default search is also used when in MFSTEST mode, whereas the old default search is not.

Device format selection is based upon the features of the destination terminal as defined at IMS system definition. If feature selection is used, a device format must be created for every combination of features in the system that can receive a message using feature selection. Feature selection is performed based on the specification of the message descriptor (MOD or MID). If the IGNORE option is specified on the MOD, device formats must be created with the IGNORE feature option to ensure proper operation.

Because the screen size for 3270 or SLU 2 devices, other than 3270 model 1 or 2, is specified during IMS system definition, an IMS system definition must be performed before execution of the MFS language utility for user-defined formats.

Use feature selection when devices with different feature combinations are to receive or enter a message and the special features of each device are to be used.

For example, an operator at a device with program function keys can enter a literal in a field using a program function key, and another operator at a device without program function keys can enter the same literal by typing it in a field on the screen. To the application program, these literals are the same. To the application program, the following input devices can enter messages that can look identical regardless of how they were entered:

• Device Features
• Print Line 120
• Print Line 126
• Print Line 132
• Data Entry Keyboard
• Program Function Keys
• Selector Light Pen Detect
• Magnetic Card Reading Devices (OICR and MSR)
• Dual Platen
• User-defined features for the 3270, SCS1, and SCS2 devices and DPM programs

Use the device feature indicator values listed in the following table for byte 2 of the DEV FEAT= specification: