So assuming symmetry, I think there are no missing dimensions (that is, left holes are 55mm off the left edge, and 20mm off the top/bottom, right holes are 20mm from right/top/bottom); tolerances, perhaps? I suspect based on what this IS that the tolerances are going to be pretty loose besides hole locations, plus counterbore depth being deep enough to cover the bolt heads.
The chamfer dimensions (the 90 degree ones) are pretty confusing,but with the size dimensions of the chamfer make it clear this is a 45 degree chamfer. The top-right view is quite confusing TBH, I THINK it just means that the counterbores for the two holes go all the way down to the 'non chamfered' surface (that is, half way down to the block).
That said, I have no idea how this works. Don't things usually have to bolt TO these tool posts? All I see are 4 spots to bolt this down to the crossslide.