This part of the Technical Specification defines the representation of ID-tags as a Postal-4i symbology 4-state bar code printed on the front side of small letters. Postal-4i symbology 4-state encoding is the only encoding specification supported by this Technical Specification ) for the printing of ID-tags on the front of items. NOTE Representation in the form of fluorescent BNB bar codes printed on the reverse side of small letters (not flats) is covered in CEN/TS 15844-2 and CEN/TS 15844-3.