John,
Yes I don't doubt you need clarification. 
Surprisingly the sliding doors are not the main entrance out of the basement. That door is right beside the door that enters the room from the rest of the basement. I will show it on a drawing that I will send with the room dimensions tonight, I hope.
The layout room is an addition that supports the sunroom above. After my in-laws moved here following the death of my wife's grandmother (the original owner) they decided to replace the small deck with a sunroom. The trainroom was only built to support the sunroom so to speak. So the door to the train room and the door to the outside take the place where the sliding glass which were originally the only way out. My mother-in-law insisted on reusing the sliding glass doors even though all they were going to use the room for was storage. My wife and I thought it would have been better if they just put a window there and discard the sliding glass door.
So, the sliding glass door is seldom opened, but I want to keep access in case we want to open it at some time. Blocking the door with a removable bridge or section would be fine.
I'll show it on the drawing.
