## Current algorithm:
1. If the timevalue is TEXT → ISO8601 ("YYYY-MM-DD HH:MM:SS.SSS")
2. If the timevalue is numeric and followed by 'unixepoch' → Seconds since 1970-01-01
3. If the timevalue is numeric → Days since -4713-11-24 12:00.
## Proposed New Algorithm (2nd Edition):
1. If the timevalue is TEXT → ISO8601 as before
2. If the timevalue is numeric and followed by 'unixepoch' → Seconds since 1970-01-01
3. If the timevalue is numeric and greater than or equal to 5373484.5 → Seconds since 1970-01-01
4. If the timevalue is numeric → Days since -4713-11-24 12:00.
In prose: if the timevalue is numeric, but would not make sense as a Julian
day number because it codes for a day beyond 9999-12-31, then interpret the
time value as a unix timestamp even if the 'unixepoch' modifier is omitted.
Otherwise, everything is as before.