<?php
$fdf = fdf_create();
fdf_add_doc_javascript($fdf, "PlusOne", "function PlusOne(x)\r{\r return x+1;\r}\r");
fdf_save($fdf);
?>
will create a FDF like this:
%FDF-1.2
%âãÏÓ
1 0 obj
<<
/FDF << /JavaScript << /Doc [ (PlusOne)(function PlusOne\(x\)\r{\r return x+1;\r}\r)] >> >>
>>
endobj
trailer
<<
/Root 1 0 R
>>
%%EOF