Do you have a specific concern? If so asking that may get you a clearer answer.
In terms of defination of night and day...check the UK ANO. It probably does one of two things
1) Defines night and day worlwide for a G reg aircraft, or
2) Deindes night and day in the UK and elsewhere unless the authority of the other country gives a different definatio.
The Irish equilivant does the second option.
dp