[Paraview] File Format Based on diffs?

[AJ Guillon]

Is there a file format for Paraview that stores diffs rather than data  
for the whole model?  Right now I use a PVD file with many VTP files  
representing a time series. However, muh of the data between VTP files  
is identical.  Is there a format that will conserve space by looking  
only at the differences between two timesteps (this is how svn works  
for instance)?

AJ