Help me decode this mechanical drawing of an SD card PCB layout
If an offset isn't given from the center-line or some other point, it should be symmetrical about the c.l. (always has been in my experience).  So 4.7 mm between the inside of GND3/GND4 would mean they are each 2.35 mm away from the c.l., likewise with the 8.3 mm outer to outer.

The pins appear to correspond to the SD card pinout I looked up.  It appears backwards on the footprint because the actual SD terminals would be on the right side, but the contacts lead to the left to connect to the board.