[Paraview] paraview making up numbers

[John Doe]

I have devices composed of pieces using an unstructured mesh in the
xml file format.  Some of the pieces don't have data in them.  It
appears that paraview makes up numbers for these regions.  Sometimes
the numbers are unphysical, e.g. 1e+307.  Sometimes the numbers seem
to be based on data from adjacent pieces.  Is there any way to tell
paraview to use a reasonable values in regions for which data is not
presented.

This becomes important as each region (piece) of my device can have
completely different physics.

Thanks,

Juan