IOSS reader does not implement block controls
The IOSS reader does not implement block controls from selection. The Exodus reader does. In 5.9.1, open can.exo. Apply. Notice the "Check Selected Blocks" and "Uncheck Selected Blocks". In master, the IOSS reader, this is missing.
The reason these controls are so valuable is that you can GUI select a large number of blocks on a surface, and quickly turn them off. Do it again, you are one surface deeper. Quickly, you are down to the level you want. Think trying to find the pistons in a car with a thousand blocks.
@utkarsh.ayachit 5.10 or 5.11? I'm OK with either, since users can use the LegacyExodus reader...