Conversation so far:
What does the term fotsy mean?
The Andriana (noble class) and the Hova (free commoner class) were a part of Fotsy, while the Andevo (slaves) were Mainty in local terminology in  Madagascar.
Are there any other interesting aspects about the Andriana article?
Austronesian people started settling in Madagascar between 200 and 500 CE. They arrived by boats and were from various southeast Asian groups.
Was there any controversy over the Austronesian people settling in Madagascar between 200 and 500 CE?
In and after the 16th century, slaves were brought into Madagascar's various kingdoms, and social strata emerged in Merina kingdom.
How did the Andriana come into play?
During the rule of King Andriamanelo, a subset of Hova related to the king by blood came under the title Andriana
What did the Andriana do?
The Andriana caste were originally the source of nobility and they specialized in the rituals and warrior occupations in the Merina society.

Question: What were the four ranks called?
Self-contained rewrite: What were the four ranks of the Andriana called?