Usually they are near the deck surface, but those are your OE crank main bearing sizes. The OE repair manuals explain more about it.
Honda had common bearing sizes in bins marked with letters on assembly line, so after machine work to the cranks and block line boring, bores and journals were measured and their differences equated to a bearing thickness.
Once a measurement was performed, the difference between them would match one of the sizes of bearings, and a corresponding bin letter.
The letters are read normally, left to right, but I cant remember if the first letter starts at the first main bearing on the flywheel side or the timing belt side. Your service manual will show and explain which direction they are read.
Then once the block was marked with the letters/sizes, the dude actually putting the bearings in the block and main caps would know exactly which bins to grab from, and place them in the correct order. Then crank gets put in, lubed, and main caps torqued.
And on down the line it goes...