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16.8 Character Translation

Screen has a powerful mechanism to translate characters to arbitrary strings depending on the current font and terminal type. Use this feature if you want to work with a common standard character set (say ISO8851-latin1) even on terminals that scatter the more unusual characters over several national language font pages.

Syntax:

         XC=<charset-mapping>{,,<charset-mapping>}
         <charset-mapping> := <designator><template>{,<mapping>}
         <mapping> := <char-to-be-mapped><template-arg>

The things in braces may be repeated any number of times.

A <charset-mapping> tells screen how to map characters in font <designator> (‘B’: Ascii, ‘A’: UK, ‘K’: german, etc.) to strings. Every <mapping> describes to what string a single character will be translated. A template mechanism is used, as most of the time the codes have a lot in common (for example strings to switch to and from another charset). Each occurrence of ‘%’ in <template> gets substituted with the template-arg specified together with the character. If your strings are not similar at all, then use ‘%’ as a template and place the full string in <template-arg>. A quoting mechanism was added to make it possible to use a real ‘%’. The ‘\’ character quotes the special characters ‘\’, ‘%’, and ‘,’.

Here is an example:

         termcap hp700 'XC=B\E(K%\E(B,\304[,\326\\\\,\334]'

This tells screen, how to translate ISOlatin1 (charset ‘B’) upper case umlaut characters on a hp700 terminal that has a German charset. ‘\304’ gets translated to ‘\E(K[\E(B’ and so on. Note that this line gets parsed *three* times before the internal lookup table is built, therefore a lot of quoting is needed to create a single ‘\’.

Another extension was added to allow more emulation: If a mapping translates the unquoted ‘%’ char, it will be sent to the terminal whenever screen switches to the corresponding <designator>. In this special case the template is assumed to be just ‘%’ because the charset switch sequence and the character mappings normally haven't much in common.

This example shows one use of the extension:

         termcap xterm 'XC=K%,%\E(B,[\304,\\\\\326,]\334'

Here, a part of the German (‘K’) charset is emulated on an xterm. If screen has to change to the ‘K’ charset, ‘\E(B’ will be sent to the terminal, i.e. the ASCII charset is used instead. The template is just ‘%’, so the mapping is straightforward: ‘[’ to ‘\304’, ‘\’ to ‘\326’, and ‘]’ to ‘\334’.