Some Asian languages have so many written characters that they cannot all
be stored in a conventional single-byte character set. Each character,
therefore, must be represented in the 3270 data stream by a two-byte code.
GDDM supports input and output of these double-byte characters but there
are two important points to bear in mind if you are using them in
alphanumeric applications.
- Hardware
- Although you can program the input and output of double-byte
character alphanumerics on any GDDM supported terminal or
workstation, you (and the end user of the application) can
only display such alphanumerics on devices such as the IBM
PS/55 workstation and the 5550 multistation. The hardware
symbol set of these devices is a Kanji double-byte character
set (DBCS). Alphanumeric applications on these devices use
that set by default, but applications can load other Kanji
sets and Hangeul sets instead.
- Field width
- The code for a DBCS character uses twice as many bytes as the
EBCDIC code for a character of the Latin alphabet.
Alphanumeric fields for Japanese or Korean characters must be
twice as wide as the number of characters they contain.
Note: For output, you can use DBCS graphics text (see "Using double-byte
characters for graphics text" in topic 12.10) either as an
alternative to the alphanumeric output functions described here or
as a way of improving the usability of your application on
terminals that don't support DBCS. On such a device, the
application could take the hexadecimal codes entered as an
alphanumeric string by the end user and display them as DBCS
graphic text characters.
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GDDM V3R2 Base Application Programming Guide
Copyright IBM Corporation 1990, 2012