This International Standard establishes a system for the transliteration and/or transcription of Greek characters into Latin characters. This system provides for two sets of rules, each constituting a type of conversion, which are: — Type 1, transliteration of Greek characters into Latin characters — Type 2, transcription of Greek characters into Latin characters This system applies to the characters of the Greek script, independent of the period in which it is or was used, i.e. it applies to monotoniko and polytoniko scripts from all periods of Classic or Modern Greek (archaic, alexandrian, hellenistic, byzantine, katharevousa, dimotiki etc.) as well as any other form of writing using the Greek script. Definitions and explanations for the terms used (transliteration, transcription etc.) appear in Annex A. This International Standard does not strictly define which type of conversion shall be used in an application. An application that needs some kind of mapping of Greek characters into Latin characters can choose one, and only one, of these types for a specific purpose. The application must explicitly declare the type adopted. This International Standard, however, recommends a preferable way of using the various types of conversion: — Type 1 (transliteration) can be used in information exchange of bibliographic references, directory services and cases where the original text may be unavailable but still needs to be reconstituted. This type can be used in every case that requires the unique conversion of the transliterated word to its original form (Greek characters) by persons not knowing the Greek language or by machines (e.g. from information technology applications, telematic services and others from the area of communications). — Type 2 (transcription) can be used in identity cards, passports, road signs, map citations and other cases where the correct pronunciation of the Greek word takes precedence over the need for reconstitution of the original form. In cases like these, other means of ensuring the relationship between the original and the converted word can be used. A table showing one method for reversible transcription is given in Annex В (Informative). Other methods for reversible transcription may also be used. The user should be aware that ordering problems may occur as a result of the transliteration/transcription process