The Nissan Path

Well, my 88 developed some sort of issue with the timing belt (don't ask, because I haven't been able to disassemble far enough to fully diagnose yet) and the heads are coming off. My simple question is this...the head bolts....are they normal hex fasteners, or are they torx or something else odd like that? TIA!

The head bolts have a recess in the top for a 10MM allen socket. I use a 6" long 10MM allen socket with a 3/8" drive, in which I install a 3/8" to 1/2" reducer, so I can use a 1/2" impact gun to remove the bolts, and later a 1/2" drive torque wrench to install them.