The EDF file format is used by the EyeLink I, II, 1000, 1000 Plus, Portable Duo, and EyeLink 3 eye tracker and supporting applications to record eye-movements, head tracking data, and other data. It is designed to be space-efficient and flexible, allowing for complete records of experimental sessions and data. It adapts to monocular and binocular recording. While the EDF file format is an efficient storage format for eye movement data, is relatively complex to support. To make the data in EDF files accessible, the translator EDF2ASC converts the files into a text version that is easily accessible from almost any programming language.

The ASC file format consists of lines of text, with each line containing data for a single sample, event or data parameter. It is easily read, and is ordered to make most data-processing tasks straightforward. Many translation options are available, specifying the file contents.

The EDF2ASC utility reads one or more EDF files, creating text files with the same name but with the ASC extension. It scans the input file, reordering data as required, and converting samples and events into lines of text. It can also compute resolutions and instantaneous velocity for sample data. The ASC files are about twice as large as the original EDF files.