Product groups and subgroups offer a way of categorising the products you trade in.  These groups are attached to stock files on the General tab in the Product Details program.  Power-Gx uses the groups and subgroups defined by BOSSF.  These can be viewed at www.bossfederation.co.uk.  Product groups and subgroups will be pre-loaded onto your system by Calidore.  You probably will not have cause to amend these, this screen is usually used only to view information.