Typically, a 64-bit floating point (double precision) variable can represent an epoch expressed as a Julian date to about 1 millisecond precision.

The decimal parts of a Julian date:

First, the precise Julian date for the start of the Julian calendar is known, although there is some uncertainty even about that.

The 5 digit code is similar, such as 00507, where the Julian date precedes the year.

For example, al-Biruni mentioned this Julian date in the year AD 1000.

This date would correspond to the Julian date of February 26, 621, or, if from the previous year, March 8, 620.

Another, better known, date notation that is used for similar purposes is the Julian date.

For the Julian date of October 13, 1307:

The Julian date is 747 plus 500, so this case was created on September 4, 2001, the 247th day of the year.

The description within the Book of Revelation matches exactly the Constellation for the Julian date 30-9-395.