The European Data
is a simple and
flexible format for
and storage of multichannel biological and physical signals. It
by a few European 'medical' engineers who first met at
the 1987 international Sleep Congress in Copenhagen. The EDF logo is
congress logo which was the green pea
from the fairy tale "The princess and the pea" by the Danish
writer Hans Christian Andersen. With the support of
Rosenfalck, the engineers initiated the European (EC funded COMAC-BME)
project on Sleep-Wake analysis (1989-1992). They
wanted to apply their sleep analysis algorithms to each others data and
compare the analysis results. So, on a morning in Leiden in March 1990,
they agreed upon a very simple common data format. This format
became known as the European Data Format. In August 1990, all
participating labs had contributed an EDF sleep recording to the
1992 in Electroencephalography
and Clinical Neurophysiology 82, pages
391-393. Since then, EDF became the de-facto standard for EEG and PSG
equipment and multicenter research projects.
An extension of EDF, named EDF+, was developed in 2002 and is largely compatible
existing EDF viewers also show EDF+ signals. But EDF+ files can also
contain interrupted recordings, annotations, stimuli and events.
Therefore, EDF+ can store any medical recording such
as EMG, Evoked potentials, ECG, as
well as automatic and manual analysis results such as deltaplots, QRS
parameters and sleep stages. The specs are stricter
than EDF which enables automatic
localization and calibration
of electrodes. And EDF+ fixed a few major (Y2K problem,
little-endian integers, comma vs dot) and minor omissions in EDF.
EDF+ was published in
2003 in Clinical
Neurophysiology 114, pages 1755-1761. Since then, hundreds of EDF+
files and several EDF+ viewers became available on the internet.
Applications till now are mainly in Clinical Neurophysiology, Sleep,
and Cardiology. Formal standards from
can also be integrated into EDF+.
EDF and EDF+ are freely available without charge. The full
specifications are in the above-mentioned publications as well as on
this EDF website. The site also supports users and developers by
offering free downloads of files and software, a list of EDF(+)
compatible companies and further contact possibilities such as Yahoo's
Files, software and utilities are most welcome, as are companies and
developers that support EDF(+).