Receiving lines will be commonly found at official military functions. An example would be a change-of-command ceremony.
Usually, the outgoing commander will not attend the post-change-of-command reception. Instead, he or she would have had another opportunity to bid farewell to his or her Airmen, thus allowing the change-of-command reception to focus fully on the new commander.
To greet the incoming commander, the line would include the announcer (if used – they introduce the guest to the receiving line participants), the new commander, their spouse, and (If desired), immediate family members (i.e. children), ending with “the extra man” (if used). The purpose of the “extra man” is to avoid leaving a woman at the end of the receiving line. Another useful role for the “extra man” plays is to escort or direct guests to refreshments or the lounge, thus keeping the line from becoming congested right at the end of the receiving line. As is the case of the announcer, the “extra man” is not there to greet guests, simply to keep them moving.
As one going through the receiving line, at official military functions, the military member (or ranking military member) leads their spouse or date through the line. If an announcer is used, their job is to announce the guests, not to greet them…so do not offer to shake hands with them.