With some modern filesystems, the filename can contain space
characters. In this case, the AV protocol ask to `quote' a
filename, i.e. quote characters are added at the beginning and
the end of the filename. So, it is very important to use this
function all the time when you send or received AV request with
filename parameters.
Please note, some desktops use the quoting filename with drag'n
drop and argv protocol.