6 is out of date insider phraseology, only useful if you want to sound like an old fashioned JW who isn’t keeping up to date with terminology
In the mid-1990s the Watchtower Bible & Tract Society officially made it known that Jehovah's Witnesses were to immediately cease referring to the WB&TS as a source of authority. In addition, the corporation "Christian Congregation of Jehovah's Witnesses" was formed. All letterhead being sent out ceased having the WB&TS logo and began using CCoJW name.