The most comprehensive information regarding Diplomatic and Official travel can be found on the U. S. Department of State site.
If you are travelling to the United States on official business representing the Ivoirian government, another recognized government or an international organization, you may be eligible for a diplomatic (A) or an official (G) visa.
To qualify for an A-1 or A-2 visa, you must be traveling to the United States on behalf of your national government to engage solely in official activities for that government.
Qualified A visa applicants traveling to the United States for assignments of less than 90 days will be issued visas annotated “TDY” (temporary duty).
Personal employees of diplomatic/official visa holders may, under certain conditions, obtain an A-3 visa.