Right before each block of recorded data, a few specification lines are written to the EDF file to report the recording information of the trial such as mount type, sampling rate, filtering level, pupil threshold, and pupil tracking algorithm.

• RECCFG <tracking mode > <sampling rate > <file sample filter > <link sample filter> <eye(s) recorded >
  This specifies the tracking mode used (pupil-only vs. pupil-CR mode), sampling rate (250, 500, or 1000 Hz), file sample filter (0: filter off; 1: standard filter; 2: extra filter), link sample filer (0: filter off; 1: standard filter; 2: extra filter), and the eyes (L, R, or LR) recorded in the trial.

• ELCLCFG <mount configuration >
  This reports the mount configuration used to do data collection.

  Configuration	Typical Setup	Tracker Version
  HBAND	Head-mounted eye tracking	EyeLink 3
  MTABLER	Desktop, Stabilized Head, Monocular	EyeLink 1000, 1000 Plus, Portable Duo
  BTABLER	Desktop, Stabilized Head, Binocular/Monocular	EyeLink 1000, 1000 Plus, Portable Duo
  RTABLER	Desktop (Remote mode), Target Sticker, Monocular	EyeLink 1000, 1000 Plus, Portable Duo
  RBTABLER	Desktop (Remote mode), Target Sticker, Binocular/Monocular	EyeLink 1000, 1000 Plus, Portable Duo
  AMTABLER	Arm Mount, Stabilized Head, Monocular	EyeLink 1000, 1000 Plus
  ARTABLER	Arm Mount (Remote mode), Target Sticker, Monocular	EyeLink 1000, 1000 Plus
  BTOWER	Binocular Tower Mount, Stabilized Head, Binocular/Monocular	EyeLink 1000 Plus
  TOWER	Tower Mount, Stabilized Head, Monocular	EyeLink 1000, 1000 Plus
  MPRIM	Primate Mount, Stabilized Head, Monocular	EyeLink 1000, 1000 Plus
  BPRIM	Primate Mount, Stabilized Head, Binocular/Monocular	EyeLink 1000, 1000 Plus
  MLRR	Long-Range Mount, Stabilized Head, Monocular, Camera Level	EyeLink 1000, 1000 Plus
  BLRR	Long-Range Mount, Stabilized Head, Binocular/Monocular, Camera Angled	EyeLink 1000, 1000 Plus

• GAZE_COORDS < left > < top > < right > < bottom >
  This reports the pixel resolution of the tracker recording. Left, top, right, and bottom refer to the x-y coordinates of the top-left and bottom-right corners of display.

• THRESHOLDS < eye > < pupil > < CR >
  This reports the pupil and CR thresholds of the tracked eye(s).

• ELCL_PROC < pupil tracking algorithm >
  This reports the pupil fitting processing type (i.e., ELLIPSE or CENTROID).

Immediately following a START line, several lines of data specifications may be present. These lines contain more extensive data than the START line about what data can be expected in the START...END block. These are most easily processed by creating a set of flags for each possible data option (left-eye events, right-eye samples, sample velocity, etc.), clearing these when the START line is encountered, and setting the appropriate flags when keywords ("LEFT", "VEL", etc.) are encountered in a data specification line.

• PRESCALER < prescaler >
  If gaze-position data or gaze-position resolution are used for saccades and events are used, they must be divided by this value. For EDF2ASC, the prescaler is always 1. Programs that write integer data may use a larger prescaler (usually 10) to add precision to the data.

• VPRESCALER < prescaler >
  If velocity data is present, it must be divided by this value. For EDF2ASC, the prescaler is always 1. Programs that write integer data may use a larger prescaler (usually 10) to add precision to the data.

• PUPIL < data type >
  This specifies the type of pupil size data (AREA or DIAMETER) recorded in the trial..

• EVENTS < data type > < eyes > < data options >
  This specifies what types of data is present in event lines, as a sequence of keywords. The < data type > is either "GAZE" or "HREF". The < eyes > recorded will be one or two words, "LEFT", "RIGHT", or both. The < data options > keywords currently supported are:
  o "RES" for resolution data (both may be present).
  o "RATE" for the sample rate (250, 500, 1000, or 2000)
  o "TRACKING" for the tracking mode (P = Pupil, CR = Corneal Reflection)
  o "FILTER" for the filter level used (0=off, 1=standard, 2=extra)

• SAMPLES < data type > < eyes > < data options >
  This specifies what types of data is present in sample lines, as a sequence of keywords. The < data type > is one of "GAZE", "HREF" or "PUPIL". The < eyes > recorded will be one or two words, "LEFT", "RIGHT", or both. The < data options > keywords currently supported are:
  o "VEL" for instantaneous velocity data
  o "RES" for resolution data (both may be present).
  o "RATE" for the sample rate (250, 500, 1000, or 2000)
  o "TRACKING" for the tracking mode (P = Pupil, CR = Corneal Reflection)
  o "FILTER" for the filter level used (0=off, 1=standard, 2=extra)
  o "HTARGET" for head target distance and position information for data collected in the Remote mode of EyeLink 1000, 1000 Plus, or Portable Duo.
  o "INPUT" for recorded external device data.