no ad1s3a,b,d... on ad1s3 after bsdlabel

[Snow Mountains]

Hi

I try to understand bsdlabel.
I have former fat slice (ad1s3) on my disk and I want to make several
BSD partitions on it. I did this:

# dd if=/dev/zero of=/dev/ad1s3 bs=1k count=1024
1024+0 records in
1024+0 records out
1048576 bytes transferred in 0.318986 secs (3287217 bytes/sec)
# bsdlabel -w ad1s3
# bsdlabel -e ad1s3
(edit)
# bsdlabel ad1s3
# /dev/ad1s3:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a: 10000000       16    4.2BSD        0     0     0
  b: 10000000 10000016    4.2BSD        0     0     0
  c: 47616660        0    unused        0     0         # "raw" part, don't edit
  d: 27616644 20000016    4.2BSD        0     0     0
# newfs -U /dev/ad1s3a
newfs: /dev/ad1s3a: could not find special device
# ls /dev/ad1s3*
/dev/ad1s3
#

What I miss because I don't have ad1s3a,b,d?
If repeat same procedure on disk (big file) mounted as /dev/md0, a see
/dev/md0,a,b,d,e... after this group of commands.

thanks
SergiM