UTCModDate.txt

https://answers.microsoft.com/en-us/msoffice/forum/all/julian-date/7d23f252-272a-4e52-802e-ec3f3e616845

Microsoft uses days since Dec20 1899.

Julian date is from 

offset      start point                name
0           noon January 1, 4713 BC   Original Julian Date. No controversy.
2400000.5   midnight Nov. 17 1858     more standard Modified JD offset
2415018.5   midnight Dec. 30, 1899    Microsoft MJD offset  
2430000.0   midnight Jan. 5, 1941     some astrophysicists use this


https://stackoverflow.com/questions/5248827/convert-datetime-to-julian-date-in-c-sharp-tooadate-safe


SQLite docs
https://www.sqlite.org/lang_datefunc.html

using SQLite-
``` SQL
-- to generate current UTCModDate
SELECT julianday('now') - 2415018.5 AS UTCModDate

-- to convert UTCModDate to standard format date/time
SELECT UTCModDate,
DATE(UTCModDate + 2415018.5) AS Date,
TIME(UTCModDate + 2415018.5) AS Time,
DATETIME(UTCModDate + 2415018.5) AS DateTime
FROM EventTable

To save UTCModDate to current time in RM database
UPDATE EventTable
  SET UTCModDate = julianday('now') - 2415018.5
  
```