The specifications of Machine Readable Travel Documents (MRTD) are set out in document 9303 of the International Civil Aviation Organisation (ICAO). According to these standards, the biodata page of a MRTD is divided into two different zones:
a Visual Inspection Zone (VIZ) containing the document designation, the holder’s facial image, personal data and data concerning issue and validity.
a Machine Readable Zone (MRZ) containing some of the information from the Visual Inspection Zone in the form of a sequence of alphanumeric characters and the symbol “<”, forming two or three lines. This sequence of characters can be read by document readers in order to facilitate inspections of travel documents (OCR - Optical Character Recognition– fonts). Form of the MRZ: ID1 format (86 x 54 mm): three lines with 30 characters each, situated on the reverse side (verso) of the document. ID2 format (105 x 74 mm): two lines with 36 characters each, situated at the bottom of the biodata page or visa. ID3 format (125 x 88 mm): two lines with 44 characters each, situated at the bottom of the biodata page.
Source : Click Here