Google directory mystery

Anyone know what the gwa and alpha by...

http://directory.google.com/alpha/Top/

and

http://directory.google.com/gwd/Top/

are all about?

The common address is of course
http://directory.google.com/Top/

Anyone know?

I've managed to find the answer..

/alpha/ = directory results are alphabetical
/gwd/ = google web directory meaning reults are only from google directory (raises the question where else is the regular directory getting results buit there ya go).

I much the prefer the pagerank sorted results anyway :-)