Which file names are accepted for files for FTP upload?

To avoid errors during uploads, please use only ASCII characters for file names (and directories), i.e.:
• a-z
• A-Z
• 0-9
• . (period)
• - (hyphen)
• _ (underscore)

The following characters, for example, are not allowed:
• Umlauts (ä, ö, ü)
• Scandinavian special characters (å,Å,ø,Ø,æ,Æ)
• Other special characters (for example: č, ć, dž, đ, lj, nj, š und ž)