The following broadly outlines the starship/starbase diplomatic grading system currently used by Starfleet. Note that classes are not required to be an exact match to these facilities in order to recieve a grade; rather they must be broadly in line with the level of capability implied by the assigned grade.

 

Grade	Facilities	Classes
7	75 x Ambassadorial quarters at 250 square metres each.  2,250 x Staff quarters at 30 - 80 square metres each  4 x 2,500 square metre conference hall complexes for 600 guests each  75 x 150 square metre 40 seat briefing rooms  75 x Independant communications facilities  30% of all facilities, including interconnecting corridors, capable of supporting H, K, or L environments  Facilities for up to 400 members of the press	Galaxy, Nebula Starbases often contain  several such facilities
6	30 x Ambassadorial quarters at 210 square metres each.  900 x Staff quarters at 25 - 60 square metres each  2 x 1,500 square metre conference hall complexes for 500 guests each  30 x 150 square metre 40 seat briefing rooms  30 x Independant communications facilities  25% of all facilities, including interconnecting corridors, capable of supporting H, K, or L environments  Facilities for up to 150 members of the press	Ambassador
5	20 x Ambassadorial quarters at 100 square metres each.  400 x Staff quarters at 15 - 25 square metres each  1 x 1,000 square metre conference hall complexes for 450 guests  20 x 90 square metre 25 seat briefing rooms  20 x Independant communications facilities  15% of all facilities, including interconnecting corridors, capable of supporting H, K, or L environments  Facilities for up to 50 members of the press	Excelsior, Sovereign
4	5 x Ambassadorial quarters at 50 square metres each.  50 x Staff quarters at 15 square metres each  1 x 120 square metre conference hall complexes for 60 guests  5 x 50 square metre 15 seat briefing rooms  One independant communications facility  15% of all facilities, including interconnecting corridors, capable of supporting H or K environments	Norway, Miranda,  Lakota-type Excelsior
3	Diplomats housed in crew quarters if required  1 x 80 square metre conference room for 40 guests  2 x 40 square metre 10 seat briefing rooms  Communications via standard ships systems  15% of all facilities, including interconnecting corridors, capable of supporting H or K environments	Akira, Steamrunner, Intrepid,  New Orleans
2	Diplomatic courier function only - diplomats housed in crew quarters for short duration interstellar missions.	Defiant, Saber,  some Oberth subtypes,  Prometheus, some Runabouts
1	Diplomatic courier function only - diplomats housed in crew quarters for short duration interplanetary missions.	Most Oberth vessels,  Runabouts and shuttlecraft,  Colony transports,  Cargo and support vessels