Best source of ConTeXt documentation?

[Brooks Moses <bmoses@stanford.edu>]

In my efforts to learn ConTeXt, I'm continually getting stuck by a lack of 
having complete documentation.  For example, consider the \definestartstop 
command, which I was recently looking at.

* In the cont-enp.pdf manual, it's not mentioned.

* In the mp-cp-en.pdf manual, there's an example of it, but it's not really 
very clear what the difference is between what the "commands=" and 
"before=" options do.  In addition, there's no indication whether these are 
all the possible options or not, or whether there's any way to define a 
start/stop pair that takes an argument.

* In the source, I can find the definitions, but for that particular one 
there seems to be very little commentary, and I also suspect I'd need to be 
rather familiar with the ConTeXt core before I could understand it -- I 
certainly can't see where the "before=" goes in, for instance.

And that's about all I know about, other than doing a Google search on the 
mailing-list archives, which rarely addresses the general stuff.

Is this all due to an actual lack of documentation for ConTeXt itself, or 
is there something large and important that I'm missing?

Thanks,
- Brooks