2nd stage bootloader does not find /netbsd on sd0a

Hello all:

I tried to install to disk today from the running diskless
setup and came accross some questions and a problem.

1- What is the right offset for slice "a" on hp700?
I missed it in the manpages. disklabel -I only enters
slice c the complete disk. Editing slice a the starting point
0s is offered, but I think this will override the boot-
code, won't it?
I used 64, this is what the disk currently looks like:

5 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:    245728        64     4.2BSD      0     0     0  # (Cyl.      0*-    231*)
 b:    245760    245792       swap                     # (Cyl.    231*-    463*)
 c:   8925000         0     unused      0     0        # (Cyl.      0 -   8419*)
 e:   4096000    491552     4.2BSD      0     0     0  # (Cyl.    463*-   4327*)

the missing fsize bsize cpg/sgs  do irritate me though.
But running fsck -f passes all checks on a and e. ( / and /usr)

2- whats the difference between /usr/mdec/xxboot and sdboot?
2b- "man 8 boot" only mentions xxboot

3- my boot problem

used "installboot" and tried both xxboot and sdboot. They both
find the 2nd stage bootloader /boot at the root of sd0a

....
loading boot at 0x22800 ... done

"some blank lines"

>> NetBSD/hp700 LIF/FFS ... 1.2
>>

Boot: dk0a:netbsd

I didn't type all the text. The 2nd stage bootloader iterates through
different files it tries all without success.
The "dk0a" though irritates me. I would have expacted something like sd0a
or hd0a. Entering those at the boot prompt manually doesn't help either.
i.e. boot sd0a:netbsd

So what is the right way, or what else can I test?
All above refer to 3.99.8 from September.


Rudi