[OA5599]

Nothing odd about it. It’s quite simple. Two or more thermal plastic/glass panes with almost full vacuum in between constitutes an aircraft window. It’s heat/cold insulation.

That's not true. The outer and middle windows do not have a vacuum in the space between them. Ever notice the little hole at the bottom of the middle window? The pressure in the space between the two windows is the same as the cabin pressure. (And of course there's no vacuum between the middle and inner plastic window you can rest your head against. Those aren't air tight.)

[melancholy]

I stand corrected. You know how the aircraft window system is manufactured. I don’t understand the lack of vacuum which is much better than gas (air) insulation under normal (cabin) pressure.

I judged by what I know of Andersen windows, two panes and vacuum in-between. I thought more temperature/pressure requirements for an aircraft.