This contains the file name extension of the file uploaded. If a
file name extension is not available it may be derived from other
information. The file name extension is typically a three character
value (e.g. "txt") after the terminating period of a file name -
the FileType property does not start with a period character.
Not all platforms use file name extensions so in these cases
other information may be used to identify the type of file.
If files are uploaded from MacBinary capable Macintosh browsers
(Internet Explorer but not Netscape Navigator) the upload contains
information on the Macintosh file Creator and Type. This
information may be used to infer the file type of the uploaded
document. The inference is based firstly on the Services for
Macintosh (SFM) settings which can be altered using MacFile. If SFM
is not installed or does not provide a suitable match then a
heuristic approach is used.
In some cases no file type information will be available. In
these cases an empty string will be returned.