Research Engagement, Library
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RECOMMENDED FILE FORMATS
University of Reading Research Data Archive
Contents
Introduction: file format categories .............................................................................................................................. 1
Overview: formats for preservation and use .............................................................................................................. 1
Recommended file formats ............................................................................................................................................ 2
Acceptable file formats: general purpose ................................................................................................................... 4
Other file formats: specialist and rarely-used ............................................................................................................ 5
Further information ........................................................................................................................................................... 6
Introduction: file format categories
The University of Reading Research Data Archive will accept any file type that you choose to deposit,
but you should wherever possible aim to deposit files that are optimised for long-term preservation and
use. For these purposes, the Archive acknowledges three categories of files:
Recommended file formats: standard preservation;
Acceptable file formats: general purpose;
Other file formats: specialist and rarely-used.
Guidance on file formats with examples of recommended and acceptable formats is provided in this
document.
Overview: formats for preservation and use
To ensure your data remain accessible and usable in the long term, you should where possible deposit
files in standard preservation file formats.
Preservation formats typically encode information in a way that is software-independent or
allows interoperability between systems and applications. These are usually recognised
standard or open formats, such as OpenDocument Format (ODF), ASCII text (.txt), comma-
separated values (.csv), or XML.
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Recommended File Formats
Proprietary formats are more suitable for preservation if they are widely-used and can be
opened in different operating systems and with different programmes or applications:
examples include Microsoft Rich Text Format, Excel, and PDF.
The preferred preservation formats for representations of image, audio and video data are
those that encode the information with a lossless algorithm, such as TIFF (.tif), Free Lossless
Audio Codec (.flac), and MPEG-4 (.mp4). Unlike lossy formats (e.g. JPEG, .mp3, WMV), lossless
formats do not cause data loss when files are saved.
We recommend you deposit your files in the Archive using open, platform-independent or non-
proprietary file formats wherever possible.
Preservation formats may not always be the most accessible or usable:
Open formats may lack the formatting and functionality that allow data to be rendered,
manipulated and analysed more effectively.
Information-rich lossless formats, such as high-resolution image or video, may produce very
large files which are not suited for web access or fast processing.
In such cases you may wish to deposit files in more than one format, so that data are optimised for both
preservation and use: for example, a richly-formatted Excel file containing manipulated tabular data
might be made available alongside a CSV file of the raw numbers; or a large TIFF image file might be
deposited for preservation, and a JPEG or other compressed image file made available for web
download.
You may need to document your file formats, for example, recording the version of the software used
to generate them, and including, if relevant, details of the compression, codec and bit rate used. This
information can be entered in the Data processing and preparation activities field in the Metadata
Record; it can also be recorded in a README.txt file or other documentation file uploaded with your
data.
For general information on choosing appropriate formats for preservation and other uses, consult the
Further information references at the end of this document.
Recommended file formats
The Archive supports and recommends the following file formats. These formats are optimised for
preservation, and you are encouraged to deposit files in these formats (converted from other formats
if necessary) wherever possible.
File type Format name File extension(s)
Microsoft Powerpoint XML .pptx
Microsoft Word XML .docx
Text OpenDocument Presentation .fodp, .odp
OpenDocument Text .fodt, .odt
Plain Text .txt, .asc
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Recommended File Formats
File type Format name File extension(s)
Adobe PDF/A .pdf
Documentation Microsoft Word XML .docx
OpenDocument Text .fodt, .odt
CSS .css
HTML .htm, .html
Markup
SGML .sgm, .sgml
XML .xml
Comma separated values (CSV) .csv
Microsoft Excel XML .xlsx
Tabular
OpenDocument Spreadsheet .fods, .ods
Tab separated values .tsv, .tab
GIF .gif
JPEG 2000 .jpxml, .jp3d, .jpf, .jpm, .jpx, .jp2
PNG .png
Image/graphics
Postscript .ps
Scalable Vector Graphics (SVG) .svg
TIFF .tiff, .tif
AIFF .aiff, .aif, .aifc
Audio Free Lossless Audio Codec (FLAC) .flac
WAV .wav
Motion JPEG2000 .mjp2, .mj2
Video
MPEG-4 .m4v, .m4r, .m4b, .m4p, .m4a, .mp4
Mineset .schema, .data
Minitab syntax and output .lis, .tj
R (ascii) .rdata
SAS syntax .sas
Database
SPSS portable .por
SPSS syntax .sps
Stata syntax .do, .dct
Structured Query Language .sql
CAD .dwg
Geospatial ESRI Shapefile .shp, .shx, .dbf, .prj, .sbx, .sbn
Geo-referenced TIFF .tif, .tfw
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Recommended File Formats
Acceptable file formats: general purpose
The file formats listed below are not considered to be standard preservation formats, for one or more
of the following reasons:
they are proprietary and system-, software- or version-dependent;
they are lossy (data are lost when compression is applied);
they are not as common as formats that have been recommended above.
These are mostly general-purpose formats, and as many are widely used, it is likely that the Archive will
be able to preserve them. But preservation of data files in these formats cannot be guaranteed, and
they are deposited at your own risk.
If you wish to preserve information, formatting or functionality encoded in files in these formats, you
may deposit the original files alongside the same files converted into standard preservation formats.
For instance, you could deposit your SPSS files (.por or .sav) along with standard preservation files in
SPSS syntax (.sps) and Plain Text (.txt) data files.
File type Format name File extension(s)
Microsoft Powerpoint .ppt
Microsoft Project .mpt, .mpp, .mpx, .mpd
Text Microsoft Word .doc
WordPerfect .w51, .wp5, .wp, .wpd
Rich Text Format .rtf
Microsoft Word .doc
Documentation
Rich Text Format .rtf
EAF File .eaf
LateX .ltx, .latex
Markup PFSX File .pfsx
TeX .tex
TeX dvi .dvi
Tabular Microsoft Excel .xls
Bitmap .ddb, .dib, .bmp
Encapsulated PostScript (EPS) .epsi, .epsf, .eps
JPEG .jpeg, .jpg, .jpe
Image/graphics Microsoft Visio .vsd
Photo CD .pcd
Photoshop .psd, .pdd
VTK (Visualisation ToolKit) .vtu
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Recommended File Formats
File type Format name File extension(s)
Audio .au, .snd
FMP3 .fp, .fmp, .fp3, .fm
Audio
MPEG Audio .m4a, .mpa, .abs, .mpega
RealAudio .rpm, .ra, .ram
AVI Audio/Video Interleaved Format .avi
Flash Video .f4b, .f4a, .f4p, .f4v, .flv
MPEG .mpeg, .mpg, .mpe
Video
Ogg Vorbis Codec Compressed Multimedia .ogg
File
Video Quicktime .qtm, .mov, .qt
DBase, DBF .dbf
Microsoft Access .mdb, .accdb
Database
SPSS output file .spv, .spo
SPSS system file .sav, .gsav
BZIP2 .bz2, .bz
Compressed Archive File .zip
Archive
GZIP compressed archive file .gz
Tarball .tar
Other file formats: specialist and rarely-used
Some data may be saved in specialist or rarely-used software-dependent file formats that are domain-
specific or unique to the instruments or software from which the raw data were generated. These are
less likely to be suitable for long-term preservation, and there is a risk that in the future it will not be
possible to open the files, if the software becomes obsolete or is not easily available.
Where possible you should convert files to recommended or acceptable formats as listed above.
Original and converted files can be deposited together to maximise both current usability and long-
term accessibility.
If a file format is not listed in this document, you should ensure your documentation includes a
description of the file format and provides information about any software required to render the files.
If you have research data in file formats you are unsure about, need help converting your files to
standard preservation formats, wish to propose a file format for inclusion in this list, or have any other
enquiries, please contact us at researchdata@reading.ac.uk.
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Recommended File Formats
Further information
The National Archives. PRONOM. https://www.nationalarchives.gov.uk/PRONOM/Default.aspx
Online registry of file formats.
UK Data Service. Recommended formats. http://ukdataservice.ac.uk/manage-
data/format/recommended-formats
Recommended formats for depositing files in the UK DataService.
Wikipedia. List of file formats. https://en.wikipedia.org/wiki/List_of_file_formats#Tabulated_data
Including common scientific data formats.
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