Hmm...I did not know that! I should really have said 'eg.' instead of 'ie.'

The point of the above 'timestamp' is is to represent a specific instant in time, independent of any time zone or calendar system. You can use Unix time for this purpose.

Depends. unixtime is for seconds, if you want to record 2 things that happen ¼ second apart, they might have the same value.

Also during leapseconds, unix time does funny things, like 2 second long 'seconds'. or it goes backwards to reset etc.