The 1st digit of the file identification ('4') specifies the current syntax version number. This number would only be increased after a specified number of years, should significant changes or enhancements to the syntax be required.
The 2nd & 3rd digits of the file identification ('02') specify the current syntax release number. This number would only be incremented by one in the event of an approved technical corrigendum being issued against the syntax (e.g. 02, 03 etc.).
Users should note that the addition of the syntax release identification capability is part of a first revision to version 4 of the syntax, currently in the process of development for submission as second edition of ISO 9735-1:1998 to ISO.