Setting (locale?) for paper size

Is there some sort of identifier like locale for papersize?
I know we in the states can almost NOT buy A4 papersize, but in the LR the only place A4 is mentioned is in PDFDocument.

Generally, paper size is a function of what is available in the printer driver. If it’s not available in a specific size you can define a custom paper size.

Thank you for answering.
So, how do I access that?
In PrinterSetup there is no mention of PageSize (not papersize).
There is eg. PageHeight, so I have to do the calculation for PageSize, or is there another way?

It really depends on the OS platform and what options the driver provides. Can you elaborate what OS and what printer options are available. It’s been a while since I worked with printing and I’m not sure what you are trying to accomplish.

Any OS is what I was looking for.
I really did not want to get into drivers so I guess that what i have is what is out there via Xojo

Why do you need to know the paper size? Most of the time, all you really need is the dimensions of the printable area, which are available from the graphics object, and possibly the print resolution from the PrinterSetup, so you can scale your printing appropriately.

I probably should have posted this in Getting Started.
I need to know that so i get the placement of the margins correct. I assume it will not be adjusted automatically.
I also want flexible margins, but those margins are all based on paper sizes - correct?
I have never done this before.

The user selects the margins. That’s why you need to be able to scale your content to fit.