Thank you for two very useful answers.
The reason I asked is this:
When I export, the output PDF-file is rejected by the printing company. I have checked every setting in the export dialog, and everything is set as recommended by the company. I cannot see any errors in the PDF, and it is shown perfectly well no matter which PDF reader, browser I use. Yet it is rejected. The file is corrupt beyond repair and cannot be uploaded, it says. That's it.
I then tried to upload a file created by the print option. Everything went smoothly.
The next step for me must be to ask the printing company for a more informative error message, so we can find out if the problem lies in the file or in their control system.
Thanks for your help, it's much appreciated
peterbirch