>  > this should be covered by my above definition (text above
>  > 16\baselineskip, float area 6\baselineskip, text after  
>  > 42-(16+6)\baselineskip). 
> 
> as one possibility for specification (not the actual values but the
concept:
> which is fixed starting position with a given vertical size and one
area
> only). my question is what others  should/could be supported?

not one area but areas which can be in 0 to n columns with and without
spans. 
 
>  > I thought this was what I'd proposed.
> 
> yes, I think so, you proposed option 2. But what about:
> 
>  > >     * ...other ideas...
> 
> is there any kind of reasonable rule set that is not covered
> by my initial variations and should perhaps be supported as well?  

I don't think so. O.k., maybe we can think of an explicity given
vertical offset which is added or subtracted after each column, e.g.

tttt tttt tttt or tttt tttt tttt
tttt tttt tttt    tttt tttt tttt
tttt tttt tttt    tttt tttt tttt
AAAA tttt tttt    tttt tttt AAAA
AAAA tttt tttt    tttt tttt AAAA
tttt AAAA tttt    tttt AAAA tttt
tttt AAAA tttt    tttt AAAA tttt
tttt tttt AAAA    AAAA tttt tttt
tttt tttt AAAA    AAAA tttt tttt
tttt tttt tttt    tttt tttt tttt
tttt tttt tttt    tttt tttt tttt

a magazine designer might like this idea to have picture material going
like a sinus wave from page to page ... ;-) Or picture material always
going in the outside column and going down somewhat after each chapter
(like an index thumb).

I will zap through some design books -- maybe I will find some other
interesting variations.

Ulrich