Digital preservation format literature review

The following is the first step in the development of recommendations on digital preservation formats, a deliverable of the National Heritage Digitization Strategy. The tables summarize findings across a number of publicly available documents. They list formats for various types of media and indicate which are accepted or recommended by larger institutions for long-term digital preservation. While these tables do not yet constitute recommendations, they serve as a summary of existing practices by large memory institutions.

Table of contents

Legend of abbreviations found in column "Published documents”

Accep: accepted format. The institution will accept files in this format for long-term preservation. An accepted format may or may not be the preferred format.

Pref: preferred format. The institution prefers that files be provided in this format for long-term preservation.

Pref(+): preferred format that may also be used as an access or preservation format as well.

Pres: preservation format.

Pres(+): a preservation format, which can also be used as an access or transfer format.

PUID: PRONOM unique identifier (a unique number assigned by the PRONOM registry to a specific file format).

RAW video: video preserved in the format produced by the hardware that originally recorded the information. Because hardware varies, this term does not refer to a specific format but rather to the format that is proprietary to that hardware manufacturer.

Rec: recommended format. The institution recommends that files be saved in this format for long-term preservation.

Trans: transfer format. Files may be transferred to the institution in this format for long-term preservation. The institution may or may not convert this information to an alternate preservation format.

Explanation of table headings

Extension: if the format is for a file, this refers to the standard file name suffix (typically three or four letters in length) following the “.” This extension indicates to an operating system in what format a file is stored and thus how the file is to be handled.

Format specification: reference to any published specifications for the format in question.

Formats: includes file formats or other digital formats for information contained within a file. The format names under this heading are often given as abbreviations; an external link is provided for further information regarding the abbreviation and its underlying format.

PRONOM: an online information system about data file formats and their supporting software products. Originally developed to support the accession of electronic records held by the National Archives (UK) and the long-term preservation of such records, PRONOM is now available online to anyone.

Published documents: headers in this section include the document name, the name of the publishing institution, the date published (if available) and an online link to the source document. Information in each column of this section identifies which file formats were preferred, recommended or accepted as a transfer format by that institution.

PUID: the PRONOM unique identifier is a label assigned in the PRONOM registry that uniquely identifies file formats and their various versions; a specific version of a specific file format has a unique PUID.

Recommendation category: applies to audio where recommendations may apply to an encoding format or a file (container or wrapper) format.

Text formats

Formats Format details Published document
Extension Format specifications PRONOM PUID
Example file formats include:
Library and Archives Canada: Guidelines on File Formats for Transferring Information Resources of Enduring Value (2014) Library of Congress: Sustainability of Digital Formats:
Planning for Library of Congress Collections (2004-2015)
Library of Congress: Recommended Formats Statement (2016–2017) Harvard Library: File Format & Content Creation Guidance The National Archives (UK): Preserving Digital Records: Guidance Archives d'État (Switzerland): Formats de fichiers adaptés à l'archivage électronique à moyen et long terme (2011) National Archives of Australia: Long-term File Formats
Common text formats
Plain text (encoding) not applicable UTF-8, UTF-16, ISO-8859-1, ISO-8859-15 or US-ASCII x-fmt/111
x-fmt/22
x-fmt/283
trans - rec - trans pres pres
ODF .odt, .ott ISO/IEC 26300:2006, Information Technology – Open Document Format for Office Applications (OpenDocument) v1.0 fmt/136
fmt/290
fmt/291
trans - - - trans - accep/pres
XML .xml - XML: fmt/120 fmt/121
fmt/101
fmt/896
- pref rec - trans - -
SGML .sgml - x-fmt/195 - pref - - - - -
EPUB .epub - fmt/483 trans - - - - - -
PDF/A .pdf - PDF/A: fmt/95 fmt/354
fmt/476
fmt/477
fmt/478
fmt/479
fmt/480
fmt/481
trans pref rec pres trans pres -
PDF .pdf - fmt/559
fmt/560
fmt/561
fmt/562
fmt/563
fmt/564
fmt/565
fmt/558
fmt/14
fmt/15
fmt/16
fmt/17
fmt/18
fmt/19
fmt/20
fmt/276
fmt/95
fmt/354
fmt/476
fmt/477
fmt/478
fmt/479
fmt/480
fmt/481
fmt/493
fmt/144
fmt/145
fmt/157
fmt/146
fmt/147
fmt/158
fmt/148
fmt/488
fmt/489
fmt/490
fmt/492
fmt/491
- pref rec pres trans - -
Word (binary) .doc - x-fmt/329 fmt/473
fmt/609
fmt/39
x-fmt/273
x-fmt/274
x-fmt/275
x-fmt/276
fmt/37
fmt/38
x-fmt/131
x-fmt/42
x-fmt/43
fmt/40
x-fmt/44
fmt/523
fmt/412
fmt/754
fmt/892
fmt/494
x-fmt/129
- - - pres trans - -
Word (xml) .docx - fmt/412 - - - pres - - -
Rich text .rtf fmt/969
fmt/45
fmt/50
fmt/52
fmt/53
fmt/355
- - - pres trans - -
HTML .html - fmt/103
fmt/96
fmt/97
fmt/98
fmt/99
fmt/100
fmt/471
fmt/102
fmt/583
- pref - - - - -
Open Office Writer .sxw - fmt/128 - - - - trans - -
WordPerfect (different versions) .wpd - WPD: x-fmt/44 x-fmt/203
x-fmt/393
fmt/949
x-fmt/394 fmt/892
- - - pres trans - -
Other text formats
OEBPS.1.2, (Open eBook Publication Structure, version 1.2, for novels, textbooks, scholarly monographs, etc.) not applicable Open eBook Forum Publication Structure 1.2 none - pref - - - - -
DTB (Digital Talking Book, ANSI/NISO Z39.86 with full transcript of text for novels, textbooks, scholarly monographs, etc.) not applicable ANSI/NISO Z39.86 none - pref - - - - -
Journal Archiving and Interchange Document Type Definition (DTD). For articles and e-journals not applicable NLM Journal Archiving and Interchange Tag Suite x-fmt/315 - pref - - - - -
Microsoft Word Template .dot .dot - x-fmt/45
fmt/755
- - - - trans - -
XML Schema Definition .xsd - XML: fmt/120 fmt/121
fmt/101
fmt/896
- - - - trans - -

Still image formats

FORMATS FORMAT DETAILS PUBLISHED DOCUMENTS
Extension Format specifications PRONOM PUID Library and Archives Canada: Guidelines on File Formats for Transferring Information Resources of Enduring Value (2014) Library of Congress: Sustainability of Digital Formats:
Planning for Library of Congress Collections (2004-2015)
Library of Congress: Recommended Formats Statement 2016–2017 Harvard Library: File Format & Content Creation Guidance The National Archives (UK): Preserving Digital Records: Guidance Archives d'Etat (Switzerland): Formats de fichiers adaptés à l'archivage électronique à moyen et long terme (2011) National Archives of Australia: Long-term File Formats McMaster University, Digital Archive: Preservation Policy (2013)
Common still image formats
TIFF (raster) .tiff, .tif TIFF Revision 6.0 Final – June 3, 1992, Adobe Systems Incorporated (PDF format) fmt/353 (many other versions) trans pref rec pres trans trans - pres
JPEG2000 (raster) .jp2 ISO/IEC 15444-1:2004, Information technology – JPEG 2000 image coding system: Core coding system
Overview of JPEG 2000
x-fmt/392 trans pref rec pres trans - - -
JPEG (raster) .jpeg, .jpg fmt/42
fmt/43
fmt/44
- pref(+) rec pres(+) trans - accep/pres -
PNG (raster) .png ISO/IEC 15948:2004, Information technology – Computer graphics and image processing – Portable Network Graphics (PNG): Functional specification
fmt/11
fmt/12
fmt/13
trans pref rec - trans - pres -
GIF (raster) .gif - fmt/3
fmt4
- pref rec pres trans - - -
PDF (various versions, PDF/A preferred) .pdf trans pref - - - pres accep/pres -
DNG (raster) .dng - fmt/436
fmt/152
fmt/437
fmt/438
fmt/730
- - rec - trans - - -
BMP (raster) .bmp fmt/114
fmt/115
fmt/116
fmt/117
fmt/118
fmt/119
- pref rec - trans - - -
Open Document Graphics (raster) .odg .otg - fmt/139
fmt/296
fmt/297
- - - - trans - accep/pres -
Scalable Vector Graphics (vector) .svg fmt/92
fmt/413
- pref rec - - - accep/pres -
OpenOffice Draw (vector) .sxd - fmt/127 - - - - - - trans -
Corel Draw CDR (vector) .cdr - fmt/467
x-fmt/375
x-fmt/378
fmt/427
fmt/466
x-fmt/379
fmt/465
fmt/464
x-fmt/29
x-fmt/291
x-fmt/292
x-fmt/374
fmt/428
fmt/429
- - - - - - trans -
Microsoft Visio Drawing (vector) .vsd - x-fmt/258
x-fmt/259
fmt/433
x-fmt/113
- - - - - - trans -
Other still image formats
AutoCad Drawing Interchange Format .dxf DXF Reference many versions - pref - - - - - -
Encapsulated Postscript .eps - - - - rec - - - - -
Shape files .shp, .shx, .dbf - - - - rec - - - - -

Moving image formats

FORMATS FORMAT DETAILS PUBLISHED DOCUMENTS
Extension Format specifications PRONOM PUID Library and Archives Canada: Guidelines on File Formats for Transferring Information Resources of Enduring Value (2014) Library of Congress: Sustainability of Digital Formats:
Planning for Library of Congress Collections
(2004-2015)
Library of Congress: Recommended Formats Statement 2016–2017 Harvard Library: File Format & Content Creation Guidance The National Archives (UK): Preserving Digital Records: Guidance Archives d'Etat (Switzerland): Formats de fichiers adaptés à l'archivage électronique à moyen et long terme (2011) National Archives of Australia: Long-term File Formats Digital Preservation Office at the University of Michigan:
A Quick Guide to Digital Video Files (2010)
Digital Preservation Coalition:
Preserving Moving Pictures and Sound (2012)
McMaster University, Digital Archive: Preservation Policy (2013)
Common moving image formats
AVI .avi - fmt/5 trans - - - - - - - - pres
MPEG-1 .mpg, .mpeg - x-fmt/385
fmt/649
- pref - - trans - - - - -
MPEG-2 .mpg, .mpeg - x-fmt/386 - pref - - trans - - pres - -
MPEG-4 .mp4 .m4v . M4a .f4v .f4a - fmt/199 - pref - - trans - - pres - -
Quicktime (MOV) .mov, .qtm - x-fmt/384 trans - - pres trans - - - - -
MXF .mxf - fmt/200 trans - - pres trans - - - pres -
WMV .wmv, .asf - fmt/133 - - - - trans - - - - -
FLASH .swf - fmt/104
fmt/105
fmt/106
fmt/107
fmt/108
fmt/109
fmt/110
- - - - trans - - - - -
OGG .ogg, .ogv - fmt/203
fmt/945
- - - - trans - accep/pres - - -
Motion JPG2000 .mj2 .mjp2 .m2v - fmt/337 - - - - trans - - - - -
Digital Cinema Initiative Distribution Master (DCDM) not applicable Digital Cinema Initiatives, DCI Specification Version 1.2, 2012

SMPTE 428-1-2006: D-Cinema Distribution Master (DCDM) – Image Characteristics
not applicable - - trans - - - - - - -
Digital Moving Picture Exchange (DPX) .dpx SMPTE ST 268:2003, File Format for Digital Moving-Picture Exchange (DPX) Version 2.0 fmt/193 (1.0)
fmt/541 (2.0)
- - trans - - - - - - -
WebM .webm fmt/573 - - - - - - trans - - -
Matroska .mkv - fmt/569 - - - - - - - accep/pres -
Other moving image formats
RAW video various - mixed - - - - - - accep/pres - - -

Audio formats

FORMATS FORMAT DETAILS PUBLISHED DOCUMENTS
Extension Recommendation category Format specifications PRONOM PUID Library and Archives Canada: Guidelines on File Formats for Transferring Information Resources of Enduring Value (2014) Library of Congress: Sustainability of Digital Formats:
Planning for Library of Congress Collections
(2004-2015)
Library of Congress: Recommended Formats Statement 2016-2017 Harvard Library: File Format & Content Creation Guidance The National Archives (UK): Preserving Digital Records: Guidance Archives d'Etat (Switzerland): Formats de fichiers adaptés à l'archivage électronique à moyen et long terme (2011) National Archives of Australia: Long-term File Formats Digital Preservation Office at the University of Michigan:
A Quick Guide to Digital Video Files (2010)
Digital Preservation Coalition:
Preserving Moving Pictures and Sound (2012)
McMaster University, Digital Archive: Preservation Policy (2013)
Common audio formats
BWF .wav file format Specification of the Broadcast Wave Format (BWF) (PDF format) Version 1: fmt/2
Version 2.0: fmt/527
trans pref rec - trans - - - pres -
WAVE .wav .wave container-wrapper format Multimedia Programming Interface and Data Specifications 1.0 (PDF format) fmt/6 - pref rec pres trans pres - - - pres
AIFF .aif, .aiff container-wrapper format - x-fmt/135 - pref - - - - - - - -
MPEG-4 .mp4 .m4v . m4a .f4v .f4a encoding format & container-wrapper - fmt/199 - pref
(mono, stereo and surround)
- pres trans - - - - -
MP3 .mp3 encoding format & container-wrapper ISO/IEC-11172-3:1993, Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 3: Audio

ISO/IEC 13818-3:1998, Information technology – Generic coding of moving pictures and associate audio information – Part 3: Audio
fmt/134 - pref - - trans - - - - -
FLAC .flac encoding format (may or may not be wrapped in a file format by the same name) - fmt/279 - - - - - - pres -  pres pres
OGG .ogg .oga encoding format & container-wrapper - fmt/203 - - - - - trans - - -
WMA .wma .asf container-wrapper format - fmt/132 - - - - - trans - - -
MIDI .mid file format - x-fmt/230 - - - - - trans - - -
Other audio formats
AAC_ADIF, Advanced Audio Coding (MPEG-2), Audio Data Exchange Format .aac encoding format & container-wrapper Documentation no longer available, but reproduced by the Library of Congress. not applicable - pref - - - - - - - -
QTA_AAC, QuickTime Audio, AAC Codec .aac encoding format & container-wrapper QuickTime File format from Apple Computer Inc. (note that there are two format specifications). not applicable - pref - - - - - - - -
WMA_WMA9_PRO, Windows Media Audio File with WMA9 Professional Codec .wma encoding format & Container-wrapper File format based in ASF (Advanced Systems Format) that wraps a Windows Media 9 professional audio bitstream. not applicable - pref - - - - - - - -
WMA_WMA9, Windows Media Audio File with WMA9 Codec .wma encoding format & container-wrapper File format based in ASF (Advanced Systems Format) that wraps a Windows Media 9 professional audio bitstream. not applicable - pref - - - - - - - -
AAC_ADIF, Advanced Audio Coding (MPEG-2), Audio Data Exchange Format .m4p, .m4b encoding format & container-wrapper - not applicable - pref - - - - - - - -
QTA_AAC, QuickTime Audio, codec AAC .m4p, .m4b encoding format & container-wrapper - not applicable - pref - - - - - - - -
WMA_WMA9_PRO, Windows Media Audio File with WMA9 Professional Codec .wma encoding format & container-wrapper - not applicable - pref - - - - - - - -

Bibliography

Archives d’État (Switzerland). Formats de fichiers adaptés à l’archivage électronique à moyen et long terme (PDF format) (available in French only), 2011.
Digital Preservation Coalition. Preserving Moving Pictures and Sound, 2012.
Digital Preservation Office at the University of Michigan. A Quick Guide to Digital Video Files, 2010.
Harvard Library. File Formats and Naming: Formats, n.d.
Library and Archives Canada. Guidelines on File Formats for Transferring Information Resources of Enduring Value, 2014.
Library of Congress. Sustainability of Digital Formats: Planning for Library of Congress Collections, 2004–2015.
Library of Congress. Recommended Formats Statement , 2016–2017.
McMaster University, Digital Archive. Preservation Policy, 2013.
National Archives of Australia. Long-term File Formats, n.d.
The National Archives (UK). Preserving Digital Records: Guidance, n.d.

Acknowledgements

Material found in this document was collected by Paul Durand of the Canadian Museum of History, William Vinh-Doyle of the Provincial Archives (New Brunswick) and Ern Bieman of the Canadian Heritage Information Network (CHIN). Tables were compiled by Paul Durand. All content was reviewed by members of the Digitization and Digital Preservation Discussion Group (Canada).

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