property FilenameCharset: string;
The FilenameCharset property contains the charset of file names used by server.
If server sends information about filename charset, then filenames can be received in the specified encoding. If the server does not send this information, then the names of files will be converted and will be received in the UTF-8 encoding. If the server sent the filename charset and you want to receive data in the specified encoding, you should send TScFilenameTranslationControlExtension with the DoTranslate property set to False. If you need to receive data in the UTF-8 encoding, you may send TScFilenameTranslationControlExtension with the DoTranslate property set to True.
To check if the information about filename charset was received from the server use the FilenameCharsetAvailable property.