• Introduction and Summary
• Date Converter (Find Your Birthday)
• PDF & HTML Calendar Generator
• Design
  • Introduction
  • Solar, Lunar and Lunisolar Calendars
  • Years and Leap Years
  • Months
  • Weeks and Days of the Week
  • Holy Days and Holidays
  • Calendar Comparison
  • Units
  • Notation
• Supporting Articles
  • Modulo Operator Explained
• Background
• Glossary

Notation

Dates are written as YYYY/MM/DD, or -YYYY/MM/DD for negative dates. This is a fairly recognisable international format for date notation, similar to the ISO8601 format for Gregorian dates (YYYY-MM-DD). It has the most significant units appearing first, which is convenient when comparing dates in computer programs.

Months can be specified as YYYY/MM, and anually recurring dates can be specified as MM/DD.

Single-digit days and months are therefore padded with a leading 0 to make 2 digits. Years are similarly padded to 4 digits (at least until the year 10,000, anyway), which is familiar, and distinguishes them from other parts of the date. The century is always shown, to avoid Y2K-type issues.

Separator character

The forward slash character '/' is used as the date separator, for several reasons:

• This character is commonly understood as a date separator, yet at present is only used in DD/MM/YYYY or MM/DD/YYYY formats; never in YYYY/MM/DD. The padding of years to 4 digits distinguishes Earthian dates from these other formats.
• The hyphen '-' plays the role of an optional leading minus sign (to indicate a negative year), plus, using hyphens as the separator character would make the date look like an ISO Gregorian date.
• Using periods '.' would cause confusion if the year or day was omitted from the date format, e.g. 1000.05 looks like an ordinary number, not a month.
• Similarly with commas ',' since this character is the decimal point in some countries.
• Colons ':' would make dates look like times.
• Semi-colons ';', vertical bars '|', back-ticks '`', squiggles '~', carats '^', octothorpes '#', backslashes '\' and pretty much any other punctuation characters simply look weird, not like date separators.
• There are few other options that would be convenient to use in writing as well as typing.

The only real downside of this choice of separator is that if a date is written without the year or day, e.g. 12/25, then it could be interpreted as a fraction. But this should not happen very often.

Golden Era Notation

The date can optionally be followed by "GE" for "Golden Era", to further distinguish it from dates in Gregorian or other calendars. The full format specification for a date is therefore as follows: [-]YYYY/MM/DD[ GE]