> What exactly is the relationship between a current kernel and 1.3a???

Please be a bit more careful with terms. 1.3_alpha is available, not 1.3A.
1.3_alpha is the alpha release of 1.3. 1.3A will be a stage of -current
after 1.3 comes out.

As David said, -current is the -current state of development efforts. It's
whatever is in the development tree (*) that day. There's a mailing
list just for folks who run it for warnings and other discussions.
For instance, if -current is badly broken for a bit, a warning goes
out on -current about it.

Most people get their source updates via sup, a software update protocol.
It copies source from a server to your disk so you can compile
-current if you wish.

After the release, the -current kernel (the kernel you'd get from source
from the -current tree) will claim to be a 1.3 kernel. At some step, a
big change will happen, and the kernel version will get bumped to 1.3A.

That 1.3A will not be the same thing as 1.3_alpha. Thus my wealth of
details. :-)

Letter incriments reflect some compatability change. Like the VFS system
changing, adding a new syscal (1.2C's reason), changing an interface
(adding the ability to dynamically add swap partitions got us 1.2F),
or adding a much-desired feature (bounce-buffer DMA for ISA got us
1.2G).

A letter change usually means that something other than just the kernel
needs updating. For instance, I use an AFS loadable kernel module,
and it usually breaks when the kernel version changes.

(*) Right now we're getting ready for a release, so if you try to
get the -current source off of the ftp or sup servers, you will
really get the 1.3_alpha source.

Good luck with it all!

Take care,

Bill