Dapper and OpenDAP constraints

[Benno Blumenthal]

One issue that came up in my using sequences to transmit OpenGIS simple 
features (points, lines, polygons, multipolygons) is how nesting 
interacts with constraints.  

For example, if you want the lines in a a certain box, simply 
restricting the lon,lat works pretty well.  On the other hand, if you 
want only the polygons that overlap a particular rectangular box, simply 
restricting the lon,lat to be in a certain range does not work because 
you need the pieces outside the box to maintain closed rings (or you 
need to generate new lines along the edges of the box).      I suppose 
in the profile case  one might want all the profiles that have surface 
temperatures above a certain value.

My impression was that in this latter case, it would be easy to get all 
the variables associated with temperatures above a certain value, but 
not so easy to get entire profiles that have a temperature somewhere in 
the profile above a certain value.

In other words, I think that currently the constraint operators in 
OpenDAP do not let one extract the structures expressed in the nesting.  
If I am wrong, could someone explain how one does those kinds of 
constraints?

I think having constraints/operators that utilize the nesting is an 
important piece of deciding how to use nesting to express the data.

Benno