Nagios Availability Report: meaning of a line

[ssm_mon]

Hello,

We use Nagios Core 4.2.4.

We have a doubt about Service Availabilty Reports created for a service that:
- Usually is in a CRITICAL state from 7 pm until midnight;
- Should be in OK state in the first hour after midnight;

The doubt is the following: what is the meaning of the line that exists for almost every day, with «Event Start Time» 00:00:00 and «State Type» CRITICAL?
- Does it show the result of a test run precisely at 00:00:00? (I guess Nagios certainly isn’t able to test all services and hosts simultaneously and precisely at 00:00:00…);
- Or does it show the result of the last test run before 00:00:00, since it repeats the «State Type» and the «State Information» for the period before midnight?

You can see, in Picture1 (at the end of this topic), an example of such kind of Nagios Availability Report.

I didn't find any documentation about this matter.

Can someone help us please?
Thanks in advance.