"Upload using an external programmer" on hardware specification page is TODO

Hi
I’m interested in the section Upload using an external programme on this page. Arduino IDE 1.5 3rd party Hardware specification · arduino/Arduino Wiki · GitHub
However it marked as todo.
I would like to support the external programmers for uploading sketches in my Arduino eclipse plugin but I fail to understand how to interpret the content.
For instance the content for avr isp is

avrisp.name=AVR ISP
avrisp.communication=serial
avrisp.protocol=stk500v1
avrisp.program.protocol=stk500v1
avrisp.program.tool=avrdude
avrisp.program.extra_params=-P{serial.port}

ID.name is clear.
But what about ID.communication that seems to be serial or USB?
and the protocol is mentioned 2 times. once as ID.protocol and once as ID.program.protocol. I have not seen a example where the 2 are different.

And why is there ID.XXX and ID.program.XXX?
Can I safely assume that when ID.program.tool=avrdude the upload pattern is tools.avrdude.upload.pattern?

Any help is welcomed.
Best regards
Jantje