[Dune] dune parallel matrix format, example

[Feng Xing]

Hello, 

After reading the example of parallel matrix (M.Blatt): https://www.dr-blatt.de/blog/posts/creating_a_parallel_istl_matrix/ 
and the paper (P.Bastian, M.Blatt) "On the Generic Parallelisation of Iterative Solvers for the Finite Element Method”,
I am a little confused with the parallel matrix format used in dune. 

If I understand well, each proc has an csr matrix independent, and these local matrix are used in to create a parallel operator using “OwnerOverlapCopyCommunication”.
I want to create a parallel matrix myself without using the functions shown in these example, I would like to ask if it is like PETSc, each proc contains some rows? If so, the col index is local or global? Thank you very much.

Ps. It seems there is no complete examples in dune-istl/test etc for parallel matrix. 

Best regards,
Feng Xing
Postdoc INRIA France