• START < time > < eyes > < types >
• END < time > < types > RES < xres > < yres >

START lines mark the beginning of a block of recorded samples, events, or both. The start time is followed by a list of keywords which specify the eyes recorded from, and the types of data lines in the bloc. The eyes recorded from are specified by "LEFT" for left-eye monocular, "RIGHT" for right-eye monocular, and both "LEFT" and "RIGHT" for binocular. The types of data lines included are specified by "SAMPLES" for samples only, "EVENTS" for events only, and both "SAMPLES" and "EVENTS" for both.

END lines mark the end of a block of data. The are specified, as it is possible to turn recording of samples and events on and off independently. However, this is not suggested, and for most applications the in the END line can be ignored. The two values following the "RES" keyword are the average resolution for the block: if samples are present, it is computed from samples, else it summarizes any resolution data in the events. Note that resolution data may be missing: this is represented by a dot (".") instead of a number for the resolution.