DOS 3.3 FST question

[Miguel van Bemmelen <miguelx@pasteur.fr>]

Hi, evrybody there,

I'd really be grateful if somebody could give me some info
about management of
DOS 3.3 under System 601.

I have been trying lately to work with some DOS 3.3-formatted
disks on my //GS
running on System 6.0.1. I tried unsuccesfully to format 5.25
inch disks in DOS
3.3 from the Finder. I read somewhere in this newsgroup that
the DOS3.3 FST is a
read-only extension. I supose that this is the reason for the
failure. Is this
right? Interesting enough, Copy II+ is not able either to
format 5.25 disks in
DOS3.3 when started up from the Finder. It gives an error TRACK
$00 and it exits.

The only way I can manage to perform the formatting is booting
from a ProDos
diskette containing the CopyII+ program. It seems therefore
that something in
System 6.0.1 (new ProDos?) interferes with the formatting
prcess. Now for the
questions:

1) Is there any special reason for the DOS 3.3 FST to allow
only reading but not
writing?

2) What is responsible for the interference with Copy II+
formatting?

Thanks in advance for the help.

mike