* Calendar
** Gregorian Date
**
* Date data representations
| abbreviation | Name | Calendar | Data structure | Comment |
|--------------+-------------------+----------------+-----------------------+------------------------------------------------------------------|
| gd | Gregorian Date | Gregorian | (list Y M D) | Y,M,D : Y(int)=year M(int)=month D(int) = day on month |
| isodate | ISO 8601 date | Gregorian | "YYYY-MM-DD" | string, numbers are dash separated. Follows Gregorian reckoning |
| wd | Work Date | Gregorian (*1) | "YYYYwwWW.D" | YYYY, WW and D are integers. WW is "work week". |
| jdn | Julian Day Number | Julian Day | integer | count of days since the beginning of the Julian Period |
| jd | Julian Date | | floating point number | |
| dow | Day of week | | | 0 = Sunday, 6=Saturday |
| | | | | |
** see https://en.wikipedia.org/wiki/Julian_day for discussion of Julian Date|Period|Day Number
** Work Date is a week-denominated year.
* Conversion routines