a conext menu item .. such as for example stuffit added to your contextmenu.
other examples are default folder, file buddy, igetter, dropicon, joliet access ... many common 3rd party extensions to OS9 will install some CMM, too.
"gather items" would be an example for apple script based context menu items.
context menu items are located in / system folder / Contextual Menu Items / (which is why the folder is called like that.
)
try putting something inside and it will show up. though IMO it is a bit pointless to have a shitload of apps and scripts there. i have a 3-button mouse ... but i dont really like to use the wheel as thrid button in classic ...