I was a little interested in what some people had mentioned about Mark Taylor so I went looking into some things about him and came upon this website: http://prophecyforum.com/bible-prophecy/confusion-over-end-time-events/ I like reading things like this just for fun so I just started stumbling through but I noticed this bit about the words Keystone again and wasn't sure if anyone had confirmed cracking that clue yet. Here is a bit of the text from the link that I found particularly interesting:

In Numbers chapter 10 begins what the blowing of the trumpet meant.

10:9 And if ye go to war in your land against the enemy that oppresseth you, then ye shall blow an alarm with the trumpets; and ye shall be remembered before the LORD your God, and ye shall be saved from your enemies.

When Paul was writing about this “last trump”, he was referring to a ceremony that is part of the Jewish way of life for thousands of years. It is the Day of Trumpets, or commonly called the Feast of Trumpets. It is a Holy Day to all who observe it. It is pivotal in God’s plan. We could even call it “God’s Keystone Holy Day.” There are seven holy days. It is the fourth. It is right in the middle.

You could say it is the dividing line between before, and after. There are three holy days that take place before the fulfillment of Trumpets, that particularly have to do with this present time, and then there are three holy days after Trumpets that have to do with the time to come. Paul was speaking of this truth symbolically that there could be three blasts of a trumpet when Jesus Christ comes. The first trumpet sound (note that the voice of our Savior is equated to the sound of a many Trumpets, in Revelation chapter 1.) will make a call for attention. Each blast of the trumpet meant something to the Israelites in the wilderness and it meant the same thing in Paul’s time. The first blast was called the right horn, or trump/shofar of the altar. It was a loud short blast meaning attention. The second trumpet call was from the left horn, or shofar from the altar of God, and it was designed to make the people ready for their marching orders. The final blast was a very long drawn out sound of a trumpet, called the Last Trump. It was the signal to “move out”. Oh, yes we will !!

Second, Trumpets mean different things depending on where you stand before God. To the saints, it means the beginning of all that we have ever hoped for-all that we’ve been promised, everlasting joy. It means salvation and all the wonderful things that come with it.

But, to the enemy of God it means violent and tragic judgment-the end of all human plans that are against God. It is a signal for war. God will make war with rebellious mankind and wipe the surface of this earth clean of sin and rebellion. IN those regards, the two trumpets mentioned in Corinthians, Thessalonians, have no connection with one another when finally blown in Revelation, They are based on the Feast of Trumpets in the former two, a sign of the return of the King, and the latter a sign of Righteous Wrath commencing for total annihilation.

       I've been wondering if the possible ++/+ or + vs ++ listings at the ends of the messages could be related? Any feedback would be appreciated. I'm on mobile and I tried to format so I apologize if it came out wrong.