"Piece Distribution" When loading *.vtm Block vs. Interleave

When loading a VTK Multiblock (*.vtm) I have the option of a dropdown box that lets me to choose Block or Interleave. What exactly does this do?
If each block is composed of multiple pieces, does it distribute the pieces when I choose Interleave? that is, distribute by piece then by block?
If I choose Block, does it distribute by Block first, then by pieces if they exist?
“Piece Distribution” does not seem to occur in ParaViewGuide-5.8.0.
Mouseover help just says “Control how datasets are loaded in parallel.”


Let  *X*  be the rank of a specific reader, and  *N*  be the number of reader, then:

* `Block`  Each processor is assigned a contiguous block of files, [ *X*  *  *N* , (  *X*  + 1) *  *N*  ).
* `Interleave`  The files are interleaved across readers,  *i*  *  *N*  +  *X* .

It doesn’t make any distinction between blocks and pieces. All leaf nodes in the multiblock dataset hierarchy are treated the same.