Strange markings on SMT resistors
After some more detective work, it seems that the strange symbol  is actually an 8. Which means that the resistor has to be read as 85X, which is EIA language for 750. The X, as suspected, is a multiplier by 0.1, so the result is 75 Ohm. This corresponds to a typical cable termination network.

I first thought all the Rs with the symbol were the same, but at the border of the camera's sight I found:



which is 68X, or, translated, is 499 times 0.1, or 49.9 Ohms.

Though I've yet to find an authoritative answer, I'm quite sure this is correct. For some reason, the rest of the resistors on the board have the 'normal' 3-digit codes.

Learned something new...