Hey Vladimir!

 MK>> ss   = two digit second ranging from 00 to 59

 VD> You have a little error on this field: sometimes the minute have
 VD> 61 seconds - for example 31 december 2016 was 23:59:60 , or
 VD> 30 june 2015 was 23:59:60 . So - this field have ranging from 00
 VD> to 60 .

That is not an error since there is no guarentee that leap seconds are
universally accepted.  Having said that I will take the liberty of dumping the
above data into coreutils-8.32 'date' and see what it thinks about it;

-={ date --date='2016-12-31 23:59:60 +0000' }=-
date: invalid date '2016-12-31 23:59:60 +0000'

-={ date --date='2015-06-30 23:59:60 +0000' }=-
date: invalid date '2015-06-30 23:59:60 +0000'

In both cases it fails.  However this works for both;

-={ date --date='2016-12-31 23:59:59 +0000' }=-
Sat 31 Dec 2016 11:59:59 PM UTC

-={ date --date='2015-06-30 23:59:59 +0000' }=-
Tue 30 Jun 2015 11:59:59 PM UTC

I read somewhere that leap seconds have to be added using a different method
and I'll probably look it up later just in case someone makes the query.  I
don't recall if they (whoever they are) cited any app where you could input the
datetime stamp in order to facillitate the above examples.  I am fairly certain
it wouldn't be found on most systems.  Certainly not any FTN abandonware I am
sure.

Life is good,
Maurice

... Don't cry for me I have vi.
--- GNU bash, version 5.1.0(1)-release (x86_64-motorshed-linux-gnu)