Waist coat? Or belt?

[The Wizard of BC]

Again a note from an old guy. One who learned to dress when people would still be able to give you the why and the reason behind what they said.

If you look at a vest they will usually have a thin satin back with the cinching strap across the back. The back of this type of vest was never supposed to be seen.
This is why I was taught that you never take your jacket off.

It is also still seen where the vest worn under the Prince Charlie Coatee did not have a back at all. It slipped over your head and had just the cinch strap going around the back.
I would never take off my jacket wearing one of these.

The Prince Charlie Coatee is the kilt equivalent of a tuxedo. It is only worn for formal occasions. You may pull the ends of your bow tie and let them hang but would never take your tux jacket off in a formal setting.

To get an idea of this type of thinking watch some old movies featuring 'The Rat Pack". This was a group of guys who did more to make the tuxedo famous than any other. Frank Sinatra, "The Chairman of the board" never took his tux jacket off except when in his private rooms. And would even put it back on before answering the door.
Dean Martin "Deano" was famous for untieing his bow tie and letting the ends hang. That was as casual or 'dressed down' as he would get.
These were guys who were masters at wearing the tuxedo. It was so natural to them that it was like they were born in them.

I try to teach this stuff to the young guys coming to my shop to rent their prom outfits. More times than I can remember these young kids have come back and thanked me for the advice from the days before blue jeans. Their dates notice this stuff and each kid has been happily surprised with the reaction he has received for dressing with just a bit more class than the others.