Support for non-3270 terminals

Minimum BMS supports only 3270 displays and printers. This category includes the 3178, 3290, 8775 and 5520, LU type 2 and LU type 3 devices, and any other terminal that accepts the 3270 data stream. The IBM® 3270 Information Display System Data Stream Programmer’s Reference manual contains a full list. Standard BMS expands 3270 support to SCS printers (3270 family printers not using the 3270 data stream) and all of the terminal types listed in Table 39. See Non-3270 CICS printers for more information about BMS and SCS datastreams.

Because of functional differences among these terminal types, it is not possible to make BMS work in exactly the same way for each of them. The sections which follow outline the limitations in using BMS on devices which lack the hardware basis for certain features.

Output considerations for non-3270 devices

Because BMS separates the device-dependent content of the output data stream from the logical content, there are only a few differences between 3270 and non-3270 devices that you need to consider in creating BMS output.

The primary difference between 3270 and non-3270 devices is that the 3270 is field-oriented, and most others are not. Consequently, there are neither field attributes nor extended attributes associated with output fields sent to non-3270 terminals. BMS can position the output in the correct places, field by field, but the field structure is not reflected in the data stream. BMS can even emulate some field attributes on some terminals (it may underline a highlighted field, for example), but there is no modified data tag, no protection against keying into the field, and so on.

If you specify attributes on output that the terminal does not support, BMS simply ignores them. You do not need to worry about them, provided the output is understandable without the missing features.

Differences on input

The absence of field structure has more impact on input operations, because many of the features of BMS depend on the ability to read--by field--only those fields that were modified. If the hardware does not provide the input field-by-field with its position on the screen, you must provide equivalent information.

You can do this in either of two ways. The first is to define a field-separator sequence, one to four characters long, in the FLDSEP option of the map definition. You place this sequence between each field of your input and supply the input fields in the same order as they appear on the screen or page. You must supply every field on the screen, up to the last one that contains any data. If there is no input in a field, it can consist of only the terminating field-separator sequence. On hardcopy devices, input cannot overlay the output because of paper movement. On displays that emulate such terminals, the same technique is generally used. Input fields are entered in an area reserved for the purpose, in order, separated by the field-separator sequence.

The second method is to include control characters in your input. If you omit the FLDSEP option from your map, BMS uses control characters to calculate the position of the data on the "page" and maps it accordingly. The control characters that BMS recognizes are:

NL new line X’15’
IRS interchange record separator X’1E’
LF line feed X’25’
FF form feed X’0C’
HT horizontal tab X’05’
VT vertical tab X’0B’
CR carriage return X’0D’
RET return on the TWX X’26’
ETB end text block X’26’
ESC escape, for 2780 X’27’

When you read data of this kind with a RECEIVE MAP command, there are some differences from true 3270 input:

Special options for non-3270 terminals

BMS provides some additional formatting options for non-3270 devices, to take advantage of device features that shorten the data stream. These include:

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