default algorithm for symmetric encryption

[vedaal]

have noticed (in gnupg 1.0.7 and 1.1.90, and as explained in the man.page)
that the default algorithm for a symmetric encryption, is the one that is
set in the option 's2k-cipher-algo name',
and not in ,
'cipher-algo name'
{although using the option 'cipher-algo name' will over-ride it}

was just curious why it was set up this way

if neither of the above options are used, it will be cast-5 by default, but
if the 's2k-cipher-algo' is set to twofish or aes256,
and then a symmetric encryption is done, it will include mdc packets
(possibly without the user intending this/or being aware
of it)

intuitively, it would seem that the default would be in the 'cipher-algo
name' option, and that if none were specified,
it would default to 3des, as this is required for all gnupg generated keys.

anyway, i'm sure there is a good reason why it is the way it is, and am just
curious about it ;)

with Respect,

vedaal