You really do learn something new every day.
I was looking at a Scale Lionel steel sided reefer the other day. It's a non operating car but I glanced through the "instruction" sheet anyway for fun. "Caution!" Do not attemp to open doors....I took this to mean maybe molded in doors, something like that.
I then noticed a small sliver of light coming through the plug door edge. Well what do you know! They do operate!
A slight tug on the handle will cause the door to pop out and travel on it's guide.
The door guide has a curved metal band that makes it act just like a real plug door. Very smooth action. 
A fun feature I didn't know existed on this reefer!
If I went by the instruction sheet I might have missed this entirely.
John
