The Extensions Manager v4.0 creates packages or groups of similar extensions by scanning all the items in the System folder and then looks at each file's VERS 2 resource. Items with identical long version string fields in the VERS 2 resources are grouped into similar areas called packages.
If the ong version string fields in the VERS 2 resources are even slightly different, a seperate package will be created. There are no packages with only 1 item in them, an example of this with an additional System Sofware package in non-PCI Power Macintosh computers that contains only 2 Ethernet extensions. This is because of a typographical error in the resource.