(registered 2022-04-29, last updated 2022-04-29)

Media type name: application

Media subtype name: xfdf

Required parameters: None

Optional parameters: charset, with the recommended value being "UTF-8" (see RFC 3023)

Encoding considerations: Binary (because XML encoding in UTF-8 is 
   limited to 1000 octets, and XFDF lines can be longer.)

Security considerations: For backwards compatibility reasons, XFDF is 
   based on XML 1.0 (5th edition) and all security considerations 
   relevant to XML 1.0 apply to XFDF. On clients, XFDF data is 
   usually combined with a PDF document and presented to an end user 
   in some form. On servers, XFDF data can be stored in databases, or 
   fed to other applications. XFDF represents only a subset of FDF 
   and may be converted to or from FDF. In all cases, it is important 
   that the data in XFDF is scrutinized to prevent malicious inputs 
   from causing damage. XFDF does not support data integrity via 
   digital signatures or data confidentiality via encryption.

Interoperability considerations: XFDF does not define an explicitly 
   encoded version number for XFDF into the XML data. Unrecognized 
   XML tags and attributes will be ignored by older processors. Older 
   versions of XFDF are thus fully compatible with newer versions of 
   XFDF. XFDF only defines a subset of FDF containing form fields and 
   annotations so conversions between these different formats can be 
   lossy.

Published specification: XFDF is defined by "ISO 19444-1:2019 
   Document management — XML Forms Data Format — Part 1: Use of ISO 
   32000-2 (XFDF 3.0)": https://www.iso.org/standard/74272.html

Applications which use this media: The XML Forms Data Format (XFDF) 
   is an XML-based equivalent subset of the FDF file format. XFDF 
   enables the exchange of a subset of form and annotation data used 
   with PDF documents using XML 1.0.

Fragment identifier considerations: XFDF does not have fragment 
   identifiers, but may be the target of a PDF fragment identifier. 
   Annex O of ISO 32000-2:2020 defines all PDF related fragment 
   identifiers. Table Annex O.4 defines the "fdf" PDF open parameter 
   which takes a relative or absolute URI argument to an XFDF file. 
   This opens the PDF document and then imports data from the 
   specified XFDF file. This information is also described 
   informatively in RFC 8118.

Restrictions on usage: None

Additional information:

   1. Deprecated alias names for this type: application/vnd.adobe.xfdf
   2. Magic number(s): none - see also RFC 3023. (RFC 3023 was the 
      current RFC at the time XFDF was originally defined and later 
      capabilities introduced via RFC 6839 and RFC 7303 are 
      incompatible with XFDF due to its backwards compatibility 
      requirements.)
   3. File extension(s): .xfdf
   4. Macintosh file type code: "XFDF"
   5. Object Identifiers: n/a

General Comments: XFDF is standardized by ISO Technical Committee 171 
   Sub-Committee 2 Working Group 8.

Person to contact for further information:

   1. Name: Betsy Fanning
   2. Email: betsy.fanning&pdfa.org

Intended usage: Common

   The XML Forms Data Format (XFDF) is an XML 1.0 based file format 
   used for a subset of PDF form and annotation data..

Author/Change controller: Committee Manager for ISO TC 171 SC 2, 
   info&pdfa.org