[Paraview] dataset questions

[John Doe]

I was going to use implement a vtk writer for my program.  I would
like to use the vtk ascii datafile format.  A few questions:

1. I have multiple regions.  Some of these regions share coordinates
at an interface.  Do I have to average the data on both sides of the
interface, or is there a way to put 2 values at the same point?  Will
paraview complain about duplicate coordinates (collinear points)?

2. Some data fields only exist in certain regions.  Does that mean I
have to set 0 values in the regions the field does not exist?

3. I have points, lines, and triangles.  If I put data on lines, does
that mean I have to define the same data fields on all of the other
cell types in my design as well?  For example, I have current flowing
along lines, but not through triangles.  So it wouldn't make sense to
have current data defined for the triangles.

Thanks,

Juan