The fdf_open() function opens a
file with form data. This file must contain the data as
returned from a PDF form or created using
fdf_create() and fdf_save().
You can process the results of a PDF form POST request
by writing the data recieved in
$HTTP_FDF_DATA to a file and open it using fdf_open(). Starting with PHP 4.3 you can also
use fdf_open_string() which handles temporary
file creation and cleanup for you.
See also fdf_open_string(),
fdf_close(), fdf_create() and
fdf_save().