I was wondering whether anyone knew the proper PDF metadata key (and value) in order to signify to PDF readers that the PDF in facing mode should be displayed from right-to-left (RTL) and not left-to-right. I use many Arabic PDFs (mainly scanned, not typed) and apparently no one encodes them properly (or whatever software they are using does not support the feature). I would like to edit the metadata so I can view pages in facing mode properly.
(I assume somebody who creates PDFs of Japanese manga, as well as Hebrew etc. documents would know this. I was unable to find a real PDF specification regarding this.)