This European Standard specifies optical characteristics for processing letters and gives guidelines onThe valuesof these attributes that will assure a high level of address readability. It is aimed at facilitating relations betweenPostal Operators and Customers by providing information that mailers can use to ensure thatThe addressesTheyprint can be processed successfully by postal automation systems.The standard is intended to support:一assessment of the probable readability of a printed address, using given address recognition equipment, without actually submitting it toThe equipment;一determination of the changes in address printing characteristics that are required to achieve a desired level of address readability using given address recognition equipment;一assessment of the complexity, and thusThe cost, of the address recognition equipment needed to achieve a desired level of readability of addresses with given printing characteristics.The standard applies to mail items whose size is up to and including C5', but may also be applied to oversizeitems, commonly referred to as CS+, and to flats.The address blocks covered are:一the delivery address block;一the sender address block ifThis is printed onThe same side of the mail item asThe delivery address block.The guidelines provided inThe standard apply to address blocks asThey appear on finished mail items whensubmitted to postal operators, and not just to addresses andThe substrate on whichThey are printed. Users of thestandard are responsible for determiningThe physical parameters which are required to achieve compliance aftertaking account of characteristics which result from mail item features, other than printing, such as covering,The useof transparent window envelopes andThe use of address labels.The guidelines are based on physical attributes that tend to influenceThe readability of addresses by opticalcharacter recognition (OCR) equipment and by video-coders. ToThe extent thatThis is possible, attributes havebeen selected so as to be easily controllable and to be measurable using simple, low-cost, means.The attributevalues given are based on common notions of typography and on colour reference systems that are likely to beknown by mailers.The values given should be interpreted as recommendations or guidelines, not as strict,mandatory, all-or-nothing rules.OCR systems are complex andTheir behaviour isTherefore not easily modelled by simple attributes. As a resultTheambition of the standard is limited byThe difficulty of defining some attributes in formal terms, even thoughTheirinfluence on address readability has been proven. WhereThis isThe case,The standard uses examples, lists ofpreferred values, or literal descriptions to give hints on how to maximise address readability.Since all attributes do not contribute uniformly toThe readability of an address,The standard identifies two levels ofsalience for each attribute (high and normal).These two levels are designed to aid inThe definition of readabilityclasses by users of the standard.This standard considers a printed address as being made up of a series of lines of printed informationZ. Guidelinesrelated to such address lines are relevant for all lines in an address block.