To ungroup:

1. ctrl+shift+a to toggle grouping on and off
2. use PICKSTYLE variable to turn grouping off

After that everything becomes single entity.

To group:

Type GROUP in the command line and follow the on screen instructions/dialog boxes. You give it a name and then select items. You can later add or remove items or explode the group.

Tip:

if youuse group for a selection of blocks,and you then explode the group, you will also explode the blocks in that group.

simply type in the command line group>select the group name,then select remove. this will avoid exploding the blocks.