Translation tables

This topic contains the following information:

TCP/IP Services uses translation tables to convert transmitted data from EBCDIC to ASCII. Because these tables do not always include all the desired characters, TCP/IP allows you to create and customize tables without having to recompile source code. Translation tables are stored in binary form on disk. TCP/IP provides standard tables that are used as the default if you do not customize your own.

TCP/IP Services used the following types of translation tables:

Single-byte character set (SBCS) translation tables are used for single-byte characters.
Double-byte character sets (DBCS) translation tables are used for converting double-byte characters. DBCS translation tables are required for character sets such as Japanese Kanji, which contains too many characters to represent using single-byte codes. SBCS translation tables provide mappings for a maximum of 256 characters. DBCS translation tables can provide up to a theoretical maximum of 65 535 character mappings; however, DBCS character sets usually contain less than this number.

The FTP program provides an FTP.DATA statement, DUMP 81, that is available for tracing the translate tables. When set on, 256 bytes of each translate table can be traced as follows:

When the FTP STAT command is entered, the translate tables being used by the server for the control and data connection is traced. When the FTP LOCSTAT command is entered, the translate tables being used by the client is traced.
When an FTP command is entered to change the translate table, the new table is traced. If the change is entered as a locsite command then it is traced by the client. If the change is entered as a site command, then it is traced by the server.
See z/OS Communications Server: IP User's Guide and Commands FTP DUMP command information for instructions on entering the command or adding it to FTP.DATA for the server and client. For all trace entries, if the trace is on the server side, it is written to syslogd. Where the client trace entries are written depends on how the client is run. If it is TSO interactive or run in OEM, the trace appears on the console. If it is a batch job, it is in the job output, and if it is being used by Rexx, it is in the Rexx output.

The FTP program also provides a multi-byte character set (MBCS) to support the Chinese standard GB18030. This support is provided by iconv with code page IBM-5488; it does not allow for customized tables. See File Transfer Protocol for a description of the ENCODING and MBDATACONN statements that define this support for FTP. Also, see z/OS Communications Server: IP User's Guide and Commands for information about how to use the LOCSITE and SITE subcommands to specify ENCODING and MBDATACONN values.

The following topics describe how to create and customize both SBCS and DBCS translation tables and explain how they are used by the programs in TCP/IP Services.