The Open eXchange Data Format, or OpenXDF, is an open,

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...

-based standard for the digital storage and exchange of time-series physiological signals and metadata. OpenXDF primarily focuses on

electroencephalography Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignal, bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in ...

and

polysomnography Polysomnography (PSG) is a multi-parameter type of sleep study and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Greek πολύς ('' ...

History

Neurotronics began work on OpenXDF in 2003 with the goal of providing a modern, open, and extensible file format with which clinicians and researchers can share physiological data and metadata, such as signal data, signal montages, patient demographics, and event logs. Neurotronics released the first draft of the OpenXDF Specification just before the 18th meeting of the Associated Professional Sleep Societies in 2004. Neurotronics has since relinquished control of the format to the OpenXDF Consortium. As of version 1.0, OpenXDF is 100% backward compatible with the European Data Format (EDF), the current de facto standard format for physiological data exchange.

Features

Tiered structure

OpenXDF is a tiered framework designed to allow standardized and custom specializations of the format while enforcing a common foundation that provides a high-level of compatibility between unrelated systems.

Metadata

OpenXDF expands on EDF by providing standardized support for extensive patient information, display montages, annotations, and scoring information.

Unicode support

OpenXDF requires the use of a XML 1.0 compliant parser that supports

UTF-8 UTF-8 is a character encoding standard used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode Transformation Format 8-bit''. Almost every webpage is transmitted as UTF-8. UTF-8 supports all 1,112,0 ...

and

UTF-16 UTF-16 (16-bit Unicode Transformation Format) is a character encoding that supports all 1,112,064 valid code points of Unicode. The encoding is variable-length as code points are encoded with one or two ''code units''. UTF-16 arose from an earli ...

Signal configuration

OpenXDF supports fully and independently configurable data signals. Each signal specifies its byte order, whether its samples are signed, the size of its samples, and its sampling rate.

Security

OpenXDF supports encryption of the XML file using

TwoFish In cryptography, Twofish is a symmetric key block cipher with a block size of 128 bits and key sizes up to 256 bits. It was one of the five finalists of the Advanced Encryption Standard contest, but it was not selected for standardization. Two ...

in Cipher Feedback (CFB) mode with a 256-bit key created from a UTF-8 encoded password hashed with

SHA-256 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compressi ...

. In addition, OpenXDF supports integrity verification using a

SHA-512 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression ...

hash of the original XML file.

References

OpenXDF Web SiteOpenXDF Specification

External links

European Data Format (EDF) Specifications
Electroencephalography Industry-specific XML-based standards {{compu-neuro-stub