FilenameToFTP renames files and folders for a next-coming FTP-upload that way, that it replaces invalid characters with an underscore "_". German special character as �, �, �, � will be replaced with "ae", "oe", "ue" and "ss". The filename will be lowercased and the file gets the current date, so it's easier to differ from earlier uploaded files.
On unix-based internet-servers it makes a big difference, whether the characters of a filename is lower- or uppercase. If you upload a program as "FilenameToFTP.Zip" on a FTP-server for example, but you point in a link to "filenametoftp.zip", so the programm won't be found by a browser online, even though at your local system all seems to be alright, because your windows-system will match the right name automatically, which is not the case in the internet. The same effect will occur with special characters as the german umlauts.
Safe characters are a-z, 0-9 and the underscore. FilenameToFTP does the job for you, to rename the file, so you can safely upload it to a ftp-server and later have no problem, they will be found, same as on your local system. For that, you should use FilenameToFTP every time, before you upload a file to your server. In addition the program sets the file-date to the current one (so it looks like you have edited it just today the last time), so it's easier to you to differ from earlier uploaded files and to find out, what file you have to upload, when you search them with your window-find-function with date-option.