What is without dispute the Day of the Lord?

Another point which is a very important is to establish what starts the Day of the Lord. The Day of the Lord is an event that contains a lot of other events. The question here is what events do they contain? Also this part splits up churches with different viewpoints on the matter of Rapture. And of course the Day of the Lord itself. 

Investigation focus:

We here seek to find the Words that define the Day of the Lord. If we can establish that we have another anchor point for the Truth.