An ODT file text document was set to A4 paper size (21.0 x 29.7cm, 8.27 x 11.69 inches), but exporting (File → Export as PDF) as PDF, LibreOffice creates incorrect PDF paper size - 8.26 x 11.69 inches! Correct PDF A4 size must be 8.27 x 11.69 inches. I think it’s a software bug.
Libre Version: 5.2.3.3
Interesting Question. And this is my best guess and stand to be corrected!
A4 is actually a metric measurement of 210 x 297 millimetres. If you wish to us an Imperial conversion the paper size is approximately 8.267 x 11.692 inches. This does round to 8.27 x 11.69 inches.
However, in Postscript, as used in printer PDF files, the dimensions are rounded off to the nearest point size, as used in printing to 595 x 842 points. There are 72 points to an inch. And this gives approximately 8.26389 x 11.69444 or 8.26 x 11.69 inches! Therefore it is not an error as it appears at first glance.
You are absolutely correct.
Thank you for your detailed and clear explanation.