@uhs/universal-timestamp

Universal Timestamp

MYYY,YYY,YYY,YYY+DDD#HH:MM:SS.sss

Where

• M = Meridian flag
• Y = Year digits
• D = Day digits
• H = Hour digits
• M = Minute digits
• S = Second digits
• s = Second decimal digits

Design Goals

The Universal Timestamp should:

• be abstracted from other calendaring systems
• be easly sortable by ASCII character order
• be stored as a simple ASCII string
• represent varying precisions from billions of years to milliseconds
• represent up to at least 13.8 billion years ago

Every timestamp is the same length, regardless of offset amount or precision.

Dates are expressed as offsets in years, days, hours, minutes, seconds, and milliseconds from a meridian. The meridian is borrowed from the Gregorian calendar.

The first character identifies if the date expressed is before or after the meridian. A "<" character signifies a year before AD 1 on the Gregorian calendar, and a ">" indicates AD 1 or later.

Pre-meridian years

If a timestamp begins with "<", indicating a year before AD 1, the year is expressed with the most significant digit on the right side, the number being padded on the left with the non-precision placeholder character "-" and on the right with zeros.

For example:

UT Year	Gregorian
<231,000,000,000	123 BC
<---,---,--8,310	13.8 Billion Years Ago (Age of Universe)
<---,209,152,000	251.902 Million Years Ago (Beginning of Triassic)

Post-meridian years

A timestamp beginning with ">" indicates a year on or after AD 1. The most significant digit is on the left, the most familiar way for most people. Dates are padded on the left by zeros, and on the right by the non-precision placeholder character, "~".

In ASCII character order, the "-" preceds numbers, where the tilde "" comes after. Using the "" for a non-precision placeholder in post-meridian years helps maintain sort order.

For example:

UT Year	Gregorian
>000,000,001,492	AD 1492
>005,~~~,~~~,~~~	5 Billion years from now (expected death of the Sun)
>000,000,000,746	AD 746 (Fall of the Western Roman Empire)

Days and Times

Regardless of meridian, the plus character (+) follows the year and denotes the start of the three day digits represnting the date's day of year.

The ~ character is used as a placeholder where precision is unknown.

For example:

Timestamp	Note
>000,000,001,492+013#~~:~~:~~.~~~	January 13, 1492, Time unknown
>000,000,001,969+197#13:31:~~.~~~	July 16, 1969 at 13:31 UTC

The day, hour, minute, and second segements must contain all digits or all placeholders. This time segement is invalid: +10~#1~:4~:2~.~~.

The decimal second segement can have variable precision.