BSD disklabel partition letters in NetBSD

["Rocky Hotas" <rockyhotas%post.com@localhost>]

Hi all! :)
BSD disklabel uses letters to specify different partitions, with some
conventions, but I can not find information about them in NetBSD.
One common scheme is:

Partition a: 	root partition, /
Partition b: 	swap
Partition c: 	NetBSD portion of disk (usually the whole NetBSD slice
		in the hard disk MBR partition table)
Partition d:	whole disk
Partition e:	custom partition, with custom mount point (e.g. /home)

and so on.

1) Wikipedia (https://en.wikipedia.org/wiki/BSD_disklabel) states that:

``BSD disklabels traditionally contain 8 entries for describing
partitions. [...] Some BSD variants have since increased this to 16
partitions''.

Which is the case of NetBSD? 8, 16, another number, or a number
depending on the port?

For example, OpenBSD ``only supports up to a maximum of 15 partitions,
‘a’ through ‘p’, excluding ‘c’'' (from disklabel(5)).

2) In Section 2.2.2 of `The NetBSD Guide', a note states:

(about “c” referring to the NetBSD portion of disk and “d” referring to
the whole disk)
``The meaning of partitions “c” and “d” is typical of the amd64 port.
On most other ports, “c” represents the whole disk''

and consequently “d” is the first letter available for custom
partitions.

What are the ports following the convention of amd64, and what instead
the ports considering “c” as the whole disk?

In OpenBSD ``the ‘c’ partition is'' [I guess, always] ``reserved for the
entire physical disk'' (from disklabel(5)).

3) Again, from OpenBSD disklabel(5):

``By convention, the ‘a’ partition of the boot disk is the root
partition, and the ‘b’ partition of the boot disk is the swap partition,
but all other letters can be used in any order for any other partitions
as desired''.

As regards NetBSD: this use of ‘a’ and ‘b’ is mandatory? Or is it
possible to arbitrarily change the letter assignments? (E.g. partition
/home to ‘a’ and root partition and swap to ‘e’, ‘f’, ‘g’ ...)

Any suggestion/information about this would be very useful.
Thank you anyway,

Rocky