leading and trailing spaces are trimmed.
If type of parameter specifies it, access mode checks are done on file. So
if access mode specifies write
mode, and file is read-only then PILGETFNAME will not accept this filename
and will prompt user to enter name of writable file.
Before applying any checks the value of the parameter (which may be URL,
for instance http://, file://etc/passwd) is converted to the filename
(if it is possible). Details are given in paragraph .