[vtkusers] Output multiple data sets to a single XML file in VTK 5 and C++

[Russell Hind]

I have a structure (in C++) which stores multiple VTK datasets.  I 
currently use our own file format to serialize all the data to a single 
file.

I'd rather use VTK but is there a VTK object that can read/write 
multiple datasets to a single file?

Multiple files isn't a possible solution for us, so will have to keep 
using our own file format if not.

Cheers

Russell