Input logical page selection

An input logical page (LPAGE) determines the content of the input message that is presented to the application program. It consists of a user-defined group of related message segment and field definitions. An input LPAGE is identified by an LPAGE statement. When no LPAGE statement is present, all message field definitions in the MSG are treated as a single LPAGE. An input LPAGE identified by an LPAGE statement can refer to one or more input device pages (DPAGE).

An input DPAGE defines a device format that can be used for an input LPAGE. It consists of a user-defined group of device field definitions. An input DPAGE is identified by a DPAGE statement. When no DPAGE statement is present, all device field definitions following the DIV statement are treated as a single DPAGE. If multiple DPAGEs are defined, each DPAGE statement must be labeled. A DPAGE identified by a labeled DPAGE statement must be referred to by an LPAGE statement.

3270 and SLU 2 device input data is always processed by the currently displayed DPAGE. For other devices, if multiple DPAGEs are defined in their formats, a conditional test is performed on the first input record received from the device. The results of this test determine which DPAGE is selected for input data processing. The LPAGE that refers to the selected DPAGE is used for input message formatting.

If input LPAGEs are not defined, message fields can refer to device fields in any DPAGE, but input data from the device for any given input message is limited to fields defined in a single DPAGE.