The simplest prototypes of the World Double Calendar - double official state calendars
of Israel, the United Arab Emirates, Saudi Arabia etc.: i.e. solar + lunar (lunar-solar)
calendars working officially simultaneously.
Unfortunately, in the given calendars the 7-day's week based on a Hebrew myth, not
reflecting a natural lunar cycle is applied.
The World Dual PETIN-METON Calendar is organized in such a manner that the same
date of any lunar month always falls on the same day of a week and always coincides with
the same Moon phase.
