XIFF (eXtended Image File Format, Xerox Image File Format), also known as XIF (eXtended Image Format, Xerox Image Format) and also DigiPaper/XIF, and apparently also Xerox DIFF, is a raster graphics format associated with ScanSoft and Xerox. It is a compound image format, similar in concept to Mixed Raster Content or JPM.
XIFF is probably considered to be proprietary, though the MIME type registration indicates that there was a specification at the (long dead) URL http://www.xerox.com/xis/xiff/.
Also used as the file format for Fax software such as the FaxWave service.
ScanSoft has a long and complicated history. It was a part of Xerox around the time XIFF was developed, and since 2005 is a part of Nuance Communications.
XIFF is an extension of TIFF. There is extension data starting at offset 8, which is not referenced by any TIFF tag. Also related to the TIFF-F specification.
XIFF is possibly related to TIFF-FX mixed raster content subtype (See RFC 2301 & RFC 2531).
A TIFF viewer that does not support XIFF will likely either not display certain elements at all, or display them as separate pages.
XIFF 3.0 Header begins with the standard TIFF header, at offset 8 for 10 bytes contains either "
XEROX DIFF", or "
eXtended " for version 2 & 3 respectively. At offset 18 there is one byte to indicate version, followed by another byte at offset 19 to indicate a revision number. See page 25 of XIFF 3.0 spec  and this forensic book 
- Not related to the XIFF instant messaging library.
- Not related to XLIFF (XML Localisation Interchange File Format). (It's apparently a common typo to write "XIFF" instead of "XLIFF".)
See also the XIF disambiguation page.
- Pagis Pro 97 Software
- Pagis viewer software and Sample XIF file (archived)
- XnView (unconfirmed)
- Imaging for Windows (at least the version that came with Windows 98)
- Some versions of various ScanSoft software such as Pagis Pro, Pagis Viewer, TextBridge, PaperPort, OmniPage Pro, XIFF Reader
- Possible XIF code
- Canon Driver with Bundled Pagis Software
- scantips.com: XIF File Format (archived)
- scantips.com: Access existing XIF Files from Windows XP (archived)
- Wikipedia: Nuance Communications
- RFC 2301: File Format for Internet Fax specifications
- ↑ https://archive.org/download/gov.uspto.patents.application.10767044/10767044-2004-01-29-00007-SPEC.pdf, p.5
- ↑ https://web.archive.org/web/20070223154220/http://www.objectrescue.com/products/recover-file-types.html
- ↑ http://www.vincent-net.com/luc/papers/99isdm_document_talk.pdf
- ↑ http://www.dlib.org/dlib/january00/moll/01moll.html
- ↑ https://web.archive.org/web/20000512013555/http://www.callwave.com/faxviewers.html
- ↑ https://tools.ietf.org/html/rfc2306#:~:text=TIFF-F
- ↑ https://archive.org/details/MacAddict-073-200209/page/n23/mode/2up?q=xif
- ↑ https://github.com/thorsted/pronom-research-week/blob/master/XIFF/Xiff3_0.doc
- ↑ https://files.transtutors.com/cdn/uploadassignments/3103417_1_guide-to-computer-forensics-and-investigations-------pg-384--407---1-.pdf#page=11