It is common for two or more countries to commemorate an event or famous person at the same time by the issue of a stamp.
To accommodate this we will try to co-ordinate the numbering of the stamps when this has occurred. In order to accomplish this we are reserving certain numbers for this purpose. These will be in the range between xxx-yyyy-11nn and xxx-yyyy-19nn, where "xxx" represents the country code, "yyyy" represents the year, and "nn" represents the numbers for the stamps in that set. For a variety of reasons it may not be possible to co-ordinate the numbering of the stamps within a given set, but it will be attempted where it practical to do so.
|xxx-yyyy-11nn||New Year||all countries||all years||includes New Years in all calendars|
|xxx-yyyy-12nn||Europa||all countries of Europe||1956 to present|
|xxx-1995-15nn||Via Baltica Highway Project||Estonia, Latvia, Lithuanis||1995|
|xxx-yyyy-19nn||Christmas||all countries||all years||includes other non-christian December festivals and stamps to commemorate the following New Year|