(PHP 4 >= 4.3.0, PHP 5 < 5.3.0, PECL fdf SVN)
fdf_get_version — Gets version number for FDF API or file
$fdf_document = ?): stringReturn the FDF version for the given document, or the toolkit API version number if no parameter is given.
fdf_documentThe FDF document handle, returned by fdf_create(), fdf_open() or fdf_open_string().
   Returns the version as a string. For the current FDF toolkit 5.0 the API
   version number is 5.0 and the document version number
   is either 1.2, 1.3 or 
   1.4.