# Forms Data Format

# Introduction

Forms Data Format (FDF) is a format for handling forms within PDF documents. You should read the documentation at » http://www.adobe.com/devnet/acrobat/fdftoolkit.html for more information on what FDF is and how it is used in general.

The general idea of FDF is similar to HTML forms. The difference is basically the format how data is transmitted to the server when the submit button is pressed (this is actually the Form Data Format) and the format of the form itself (which is the Portable Document Format, PDF). Processing the FDF data is one of the features provided by the fdf functions. But there is more. One may as well take an existing PDF form and populated the input fields with data without modifying the form itself. In such a case one would create a FDF document (fdf_create()) set the values of each input field (fdf_set_value()) and associate it with a PDF form (fdf_set_file()). Finally it has to be sent to the browser with MimeType `application/vnd.fdf`. The Acrobat reader plugin of your browser recognizes the MimeType, reads the associated PDF form and fills in the data from the FDF document.

If you look at an FDF-document with a text editor you will find a catalogue object with the name `FDF`. Such an object may contain a number of entries like `Fields`, `F`, `Status` etc.. The most commonly used entries are `Fields` which points to a list of input fields, and `F` which contains the filename of the PDF-document this data belongs to. Those entries are referred to in the FDF documentation as /F-Key or /Status-Key. Modifying this entries is done by functions like fdf_set_file() and fdf_set_status(). Fields are modified with fdf_set_value(), fdf_set_opt() etc..

- Installing/Configuring
  - Requirements
  - Installation
  - Resource Types
- Predefined Constants
- Examples
- FDF Functions
  - fdf_add_doc_javascript — Adds javascript code to the FDF document
  - fdf_add_template — Adds a template into the FDF document
  - fdf_close — Close an FDF document
  - fdf_create — Create a new FDF document
  - fdf_enum_values — Call a user defined function for each document value
  - fdf_errno — Return error code for last fdf operation
  - fdf_error — Return error description for FDF error code
  - fdf_get_ap — Get the appearance of a field
  - fdf_get_attachment — Extracts uploaded file embedded in the FDF
  - fdf_get_encoding — Get the value of the /Encoding key
  - fdf_get_file — Get the value of the /F key
  - fdf_get_flags — Gets the flags of a field
  - fdf_get_opt — Gets a value from the opt array of a field
  - fdf_get_status — Get the value of the /STATUS key
  - fdf_get_value — Get the value of a field
  - fdf_get_version — Gets version number for FDF API or file
  - fdf_header — Sets FDF-specific output headers
  - fdf_next_field_name — Get the next field name
  - fdf_open — Open a FDF document
  - fdf_open_string — Read a FDF document from a string
  - fdf_remove_item — Sets target frame for form
  - fdf_save — Save a FDF document
  - fdf_save_string — Returns the FDF document as a string
  - fdf_set_ap — Set the appearance of a field
  - fdf_set_encoding — Sets FDF character encoding
  - fdf_set_file — Set PDF document to display FDF data in
  - fdf_set_flags — Sets a flag of a field
  - fdf_set_javascript_action — Sets an javascript action of a field
  - fdf_set_on_import_javascript — Adds javascript code to be executed when Acrobat opens the FDF
  - fdf_set_opt — Sets an option of a field
  - fdf_set_status — Set the value of the /STATUS key
  - fdf_set_submit_form_action — Sets a submit form action of a field
  - fdf_set_target_frame — Set target frame for form display
  - fdf_set_value — Set the value of a field
  - fdf_set_version — Sets version number for a FDF file

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