What are All the Columns in a Google App Engine HTTP Log?

What does all of the data in a Google App Engine HTTP log mean? For example, in the following (anonymised) log:

107.10.42.191 - foobiz [10/May/2011:17:26:28 -0700] "GET /page.html HTTP/1.1" 500 2297 "http://www.example.com/home.html" "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/5.0.3 Safari/533.19.4,gzip(gfe),gzip开发者_C百科(gfe),gzip(gfe)" "www.example.com" ms=364 cpu_ms=23 api_cpu_ms=0 cpm_usd=0.001059

I understand most of the columns, can you help fill in columns 2 and 14?

1. IP Address: 107.10.42.191
2. Just a hyphen, or something more?: -
3. Logged in user: foobiz
4. Request Time: [10/May/2011:17:26:28 -0700]
5. HTTP Request: "GET /page.html HTTP/1.1"
6. HTTP Response Status Code: 500
7. HTTP Response Size in Bytes: 2297
8. Referring Page: "http://www.example.com/home.html"
9. Browser Info: "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/5.0.3 Safari/533.19.4,gzip(gfe),gzip(gfe),gzip(gfe)"
10. Host: "www.example.com"
11. Total Time: ms=364
12. CPU Time: cpu_ms=23
13. API Time: api_cpu_ms=0
14. What is this?: cpm_usd=0.001059

I know there is a similar question on SO, but it seems outdated and wasn't really answered.

Logs are in Apache Combined Log Format, with some additional fields. The fields, in order, are:

1. Client's IP address (107.10.42.191)
2. The RFC1413 identity of the client (in practice, always '-')
3. The userid determined by HTTP authentication ('foobiz')
4. The timestamp of the request ('[10/May/2011:17:26:28 -0700]')
5. The first line of the request, containing request method, path, and HTTP protocol version ("GET /page.html HTTP/1.1")
6. The status code returned by the server (500)
7. The size in bytes of the response (2297)
8. The referer path ("http://www.example.com/home.html")
9. The user-agent ("Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-us) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/5.0.3 Safari/533.19.4,gzip(gfe),gzip(gfe),gzip(gfe)")
10. The hostname
11. The wallclock milliseconds required to fulfill the request
12. The CPU milliseconds required to fulfill the request
13. The CPU milliseconds spent by API calls
14. An estimate of the cost of 1000 requests like this, in USD.

This question has been answered here: GAE/J request log format breakdown

cpm_usd is the estimated cost of 1000 similar requests in US dollars.