Somewhere on this site I saw a page outlining the pluses of using RAT mip mapped textures and how to create them. I can't seem to find it now. Can anyone point me to it?

I found the page…

http://www.sidefx.com/dls/tutorial/webrat/webrat.html [sidefx.com]

Now I have some questions. When you save to a RAT file from anywhere in Houdini (mplay, COPs, icp, iconvert) are the mip map levels created automagically and stored within the RAT file? If so, how are the levels created? Is the resolution just successively halved? Also, is there a way to specify the number of levels you'd like to create? Additionally, can someone explain the proper way to create a RAT file in COPs? Lastly, is the file format open to the public, and if so where can I find it? I'd like to possibly load RAT files in a realtime viewer.