See Understanding IIS 7 log files. If you are using Windows 2012/IIS8, the default W3C format for those last 6 numbers is:
- sc-status
- sc-substatus
- sc-win32-status
- sc-bytes
- cs-bytes
- time-taken
You can see this in a header at the top of the file, e.g.:
#Software: Microsoft Internet Information Services 8.0
#Version: 1.0
#Date: 2014-02-12 08:00:05
#Fields: date time s-sitename s-computername s-ip cs-method cs-uri-stem cs-uri-query s-port cs-username c-ip cs-version cs(User-Agent) cs(Cookie) cs(Referer) cs-host sc-status sc-substatus sc-win32-status sc-bytes cs-bytes time-taken