This document is only relevant for Asian countries which use double-byte character sets. It describes all features implemented in Natural to support DBCS terminals and printers.
It covers the following topics:
In alphanumeric fields with SBCS and DBCS characters mixed, the DBCS character strings are separated from the SBCS strings by shift codes called SO (shift-out) and SI (shift-in). The Natural profile parameter SOSI is used to pass the values of the shift-in and shift-out codes used in the current environment to Natural.
It is strongly recommended to use the IBM characters X'0E' and
X'0F' internally. With this technique, all applications and data can be
handled in a compatible manner, which means that a network supporting different mainframe
types can still use the same Natural applications and process the same data.
For detailed information on this parameter, see SOSI.
The Natural session parameter PM=D is used to define DBCS-only fields. A
DBCS-only field must contain only valid DBCS characters; shift-out/shift-in characters
(SO/SI) are not allowed within such a field. To display a field with the session parameter
PM=D specified, the screen attribute X'43F8' is added for IBM
terminals.
The following parameters must be specified in the setup for Natural for the support of double-byte character sets:
| Parameter | Explanation |
|---|---|
TS=ON
|
If Latin lower-case characters are not available, this parameter translates
all Natural system output using the translation table defined by the macro
NTTABL in the NATCONFG module.
|
SOSI=(0E,0E,0F,0F,1) |
Defines the DBCS shift-out and shift-in values for IBM hardware. |
LC=ON
|
Does not translate all input data to uppercase, which again would destroy possible DBCS input data. |
In addition to TS=ON, further parameters to provide for translation of
messages into upper case are provided by several Natural components. For detailed
information, see Other Parameters
to Provide Upper Case Translation in the TS profile parameter
documentation.
If you want to enter DBCS or half-width Katakana characters in one of the Natural editors, the following editor general default options should be set in the editor profile to avoid that character constants or field names containing DBCS or half-width Katakana characters are unintentionally converted to upper case:
| Option | Value | Explanation |
|---|---|---|
| Editing in Lower Case | Y |
Lower-case characters in the source code are not automatically converted to upper case. This option is required if you are using DBCS or half-width Katakana characters. |
| Dynamic Conversion of Lower Case | N |
Any source code remains as you enter it. This option is required if you are using half-width Katakana characters. |
For detailed information on the editor general default options, see General
Defaults. For detailed information on the editor profile, see
Editor
Profile in the Editors documentation. To
avoid the need to change these options for every user, you can modify the default profile
for your installation by means of the user exit routine USR0070P, which also
supports DBCS; see USR0070P - User
Exit for Editor Profiles in the section Configuring
Natural.
If the session parameter PM=D is set for a field, it is verified
that the input data
contains an even number of bytes,
contains only valid DBCS characters,
does not contain shift-out/shift-in characters (SO/SI).
Because the detection of non-DBCS characters requires ICU, this check will not be performed if ICU
is not available (that is, if the profile parameter CFICU=OFF has been set).
If a window is to be displayed for user interaction, the window might overlay DBCS
characters that are already displayed, or the window might itself contain DBCS characters
which are truncated because of the window size. An overlay may also occur if the NO
ERASE option is used with an INPUT statement. In order to prevent
screen corruption in case of such an overlay, the following actions are performed to
adjust the output data, if necessary:
if the session parameter PM=D is set for a field, an orphan byte (that
is, a single byte left at the beginning or end of the data to be displayed as a result
of a partial overlay of a DBCS character) is replaced by an attribute; this operation
assures that only valid DBCS characters are displayed;
if the profile parameter SOSI has been set, the field contents of an
alphanumeric field for which PM=D is not specified is examined for
shift-out/shift-in characters (SO/SI); if a shift-out character (SO) is found for
which the correlating shift-in character (SI) is missing, either the last character of
the output data is replaced by a shift-in character (SI) or the last two characters
are replaced by a shift-in character (SI) followed by a blank; if a shift-in character
(SI) is found for which the correlating shift-out character (SO) is missing, either
the first character of the output data is replaced by a shift-out character (SO) or
the leading two characters are replaced by a blank followed by a shift-out character
(SO); this operation assures that DBCS characters are enclosed properly by
shift-out/shift-in characters (SO/SI).
To avoid unintentional interpretation of DBCS characters as delimiter or control
characters, the FORMATTED option of the STACK statement should be used if the data to be placed on
the Natural stack contains DBCS characters.
See the Statements documentation for further information on the
STACK statement.
See the Programming Guide for further information on the Natural Stack.
The following user application programming interfaces (API) are available to support DBCS handling:
These APIs are contained as subprograms in the Natural library SYSEXT.
Detailed information on how to use an API is included in the corresponding text object
(USRxxxxT). See
also SYSEXT Utility - Natural
Application Programming Interfaces in the
Utilities documentation.
The application programming interface USR4211N can be used to obtain
information on the availability of DBCS support and the defined SOSI characters.
The application programming interface USR4213N can be used to perform the
following functions:
Convert a normal Latin character string into the corresponding DBCS character string.
Convert a DBCS character string that contains Latin data only into a single-byte character string.
Add the current shift codes at the beginning and at the end of a character string.
Remove leading and trailing shift codes from a character string.
The last two functions can be used to either produce native DBCS strings or generate mixed-mode data out of native DBCS strings.
The alternate text module NATTXT2U contains certain keywords for English language in all
upper case which are contained in mixed case in text module NATTXT2.
NATTXT2U should be linked to the Natural nucleus instead of
NATTXT2 in environments where lower case code points H'81' to
H'A9' are used to display national characters.
