2
On new sites UTF-8 is choosen as character set encoding. Older use mostly an ISO (latin) variant.
It is important that you use the same character encoding set at all levels: database tables and connection, XOOPS settings.
This has also repercussions for the file formats on the server, which have to be aligned with the character set encoding choice.
The ansi format goes with ISO and UTF-8 (without BOM) with UTF-8.
This is needed for all PHP files in the language directories and for all support files, like theme, templates and some javascript files with language information. Most older modules provide the ansi format.
Conversion can be done with an editor such as Notepad++.