Thought this was interesting...I'm reading Daniel and he calls God "Ancient of Days" several times. I looked it up in the concordance, and this was the description for what the words mean
Ancient - ancient
Days - day, time
I looked up the other instances in the bible of "ancient" and "days" and the other forms had paragraph amounts of description. The hebrew word for ancient in the name Ancient of Days is only used as the name of God, only three times in the bible, all in Daniel chapt 7 which is about his vision that corresponds with Revalation of Satan & the beasts/kingdoms overturned, Christ returning and having dominion, and God's white throne of judgement.
It's like God is saying He is what He is, no explanation necessary. Kinda like with Moses when He said to tell them "I AM" sent you! I love those words!!
The Ancient of Days, same from Daniel's time, through John's time, through ours, returning victoriously to fulfill His Word!