Use case or problem
Obsidian’s PDF deep linking feature is great. However, currently Obsidian does not allow us to copy a link to a text selection that spans multiple pages (see below).
It is very common that a range of text that we want to mention in our notes (by linking) crosses the page border, but the current feature does not allow us to do that.
Single page 
Multiple pages 
“Copy link to selection” option is not shown when the selection spans multiple pages.
Proposed solution
Extend the current PDF link syntax [[file.pdf#page=<PAGE>&selection=<SELECTION>]] and allow it to link to cross-page selections.
In my opinion, the following would be the most natural candidate:
[[file.pdf#page=<PAGE A>-<PAGE B>&selection=<SELECTION>]]
<PAGE A>: the page number that the selection begins on.<PAGE B>: the page number that the selection ends on.<SELECTION>: four comma-separated integers that follow the same rule as the current one, except that the first two indicate the starting position of the selection within<PAGE A>, and the last two indicate the ending position within<PAGE B>.
Current workaround (optional)
None
Related feature requests (optional)
None on this forum.
In fact this FR was originally inspired by a FR that sent to my plugin PDF++.
Basically, PDF++ converts a link to PDF text selection to a highlight when the PDF file is opened. Since Obsidian does not support linking to cross-page text selections, PDF++ cannot highlight cross-page sentences (which is very common).
Once linking to cross-page text selections is implemented in the Obsidian core, PDF++ will able to support cross-page highlighting and this would be massively benefit users.
However it will also be very helpful for other users who don’t use PDF++.