Desiphering MS Proxy Logs

Any now where to get details on MS Proxy Log definition of the columns of info. Some of it is abvious but not all.

I do not want to spend a lot of money for a program that can desipher proxy logs.

Not just the basic info offored by MS that does’nt really tell you much, I want to import these logs into a data base but I’m not sure what to label each column.