continuous numbering of subsection

[Ulf Martin <ulfmartin@web.de>]

Dear ConTeXt Experts

I am still sometimes confused about how to set up simple things...

I want to have a subsection level head type ("topic") with a numbering 
that runs undependently from the section numbering, like so:

1. First Topic
...

I. Section One
...

2. Second Topic
...

3. Third Topic
...

4. Fourth Topic
...

II. Section Two

5. Fifth Topic
...

6. Sixth Topic
...

III. Section Three
...

And so on.

ConTeXtgarden, the manual, etc. show in great detail how to set up the 
/appearence/ of head parts (incl. numbercommand), but I cannot find an 
explanation of the handling of the LaTeX equivalent to counters (their 
definition, incrementing, resetting, etc.). The explanation of 
\setupheadnumber in the manual (p. 172) is quite obscure to me -- how do 
I specify that I do not want higher levels of head to reset my numbering?

Thank you!
Ulf Martin