Input message formats

MFS edits input data from a device into an IMS application message format using the message definition that the MFS application designer writes as input to the MFS language utility program. An input message consists of all segments presented to an IMS application program when the program issues a DL/I GU or GN call.

The format of input messages is defined to the MFS Language utility. Each message consists of one or more segments; each segment consists of one or more fields:

MESSAGE
    SEGMENTS
        FIELDS

Message field format is defined specifically to the utility in terms of data source, field length, justification, truncation, and use of fill (pad) characters. How MFS actually formats the field is a function of the formatting option selected for the message. The option used is identified in the second byte of the 2-byte ZZ field (Z2) preceding the message text. An application program that depends on MFS should check this field to verify that the expected option was used; a X'00' in the Z2 field indicates MFS did not format the message.

Logical pages

For 3270 or SLU 2, the input message is created from the currently displayed DPAGE on the device. For some other devices, if the device input format has more than one DPAGE defined, the device data entered determines which input LPAGE is selected to create an input message. However, for ISC (DPM-Bn) subsystems, OPTIONS=DNM or COND= can be used for DPAGE selection.

When LPAGEs are defined, each LPAGE is related to one or more DPAGEs.