Stumped: If an oil pan has 18 holes why does it only need 8 bolts, 4 studs & 10 nuts?

2002 Honda Civic Sedan LX 1.7L.
Pulling my hair out for days trying to figure out how many bolts & studs my oil pan needs since I don't have access underneath the car. The Pan & Gasket have 18 holes but looking at the diagram with the link below it shows I only need 8 bolts, 4 studs & 10 nuts. The math does not add up should it be a combination of 18 bolts & studs?

http://www.hondapartsnow.com/parts-list/2002-honda-civic-4dr_lx-ka-4at/cylinder-block-oil-pan.html?PartNumbers=11200-PLC-000

You are missing at least 4, the studs that go through the oil seal housing. Other than that, I don't know. Why don't you have access to underneath your car?

2 different studs are located near the rear main housing. 4 studs are built onto oil pump.

Not really worth replacing studs unless you have access to a torch or the studs are "already" loose. Auto manufacturers use a semi-permanent glue similar to loctite or threadlocker to prevent studs from backing out from the engine block that only release with heat or they could strip out the threads in the engine block.

It sounds like there are 6 studs already in the bottom of the block.