,394, etc.
File format: The file format for these timestamps is ISO 8601, which is a standard format for representing dates and times.

Here is an example of how to convert these timestamps to a human-readable format:

* 18:58 on December 25, 2017: 2017-12-25T18:58:00
* 08:00 on January 1, 1970: 1970-01-01T08:00:00

Note that the year in the timestamp is the year in which the day of the week corresponds to, so December 25, 2017 corresponds to the year 2017.

It's worth noting that the timestamp format is flexible and can be adjusted to suit your needs. For example, you could use a different format for the day of the week, such as "ddd" for "Monday", "dddd" for "Monday, December 25, 2017", or "HH:mm:ss" for "8:58 PM".