How to read syntax descriptions

[Salman Khilji <skhilji@tampabay.rr.com>]

In the beginner's manual, we have for \startitemize the following:

\startitemize[..,..,..][..,..=..,..] ... \stopitemize

I was wondering how do you read this in english?  Based on the examples, am I 
correct to say the following?

1)  The \startitemize is optionally followed by a comma separated list of 
parameters enclosed in brackets.

2) Then a set of key-value pairs enclosed in brackets follows.  Again this is 
optional.

If this is correct, then what about \setupitemize?.  It says

\setupitemize[.1.][..,.2.,..][..,..=..,..]

So again let me guess

.1. stands for a number
The third set could be key-value pairs

What about the set in the middle?

Can we have an explanation for these please.

Salman