Host(ess): The representative who welcomes the invited on arrival and whose name is mentioned on the invitation card.
Co-host(ess): All other representatives present.
Left/right: The perspective of the audience determines what is left or right.
Seating/ placement: To determine who sits on which seat.
Ushers: The employees assisting the guests in finding the right seat. In the Netherlands the employees of the Protocolbureau are commonly known as ushers.
Seniority: The concept of a person or group of people taking precedence over another person or group because the former is either older than the latter or has occupied a particular position longer than the latter.
Corps Diplomatique: The diplomatic corps or corps diplomatique is the collective body of foreign diplomats accredited to a particular country or body.
Dean (or Deken or Doyen): In some countries, the longest-serving ambassador to a country is given the title Dean, or Doyen, of the Diplomatic Corps and is sometimes accorded a high position in the order of precedence.