"Unix time format" is not a term I'm familiar with; I don't think such a thing exists.
Do you mean "UNIX time"? In that, case, yes, it's the seconds since the beginning of 1970; it's not defined how you store that, and it's not defined that it's only integer fractions. It's just the time that has passed since 1970-01-01 00:00 UTC. The resolution at which things are handled is a different question.
How you print that is yet a completely different question!
So, you'll need to mentally treat three different things:
- Time (as in: UNIX time, UTC time, GPS time… ); that's the physics.
- Time observation (as in: what resolution does my clock have?); that's the way time is internally handled by your system
- Time format (as in:
strftime
, printing time as full seconds.fractional seconds, or as "Wednesday, shortly after my first afternoon coffee"); that's the way time that was observed/internally handled is displayed.
It's not standardized, and the program you're looking at seems to have decided to print it as a decimal number. OK! The number of digits imply nanosecond resolution, which might make sense, this looks like a message from cellular infrastructure, and these things actually have a notion of nanoseconds. However, that might also imply this isn't UNIX time, but some related time that potentially deals differently with GPS leap second compensation and so on. So, you'll have to read the documentation of your software (or the cellular standard you're using, if my guess is correct).