Unit is related to Part. Part is related to Division. Division is related to Line. Line is related to Flat. 
Eye is related to Part. Part is related to Letter. Initial is a type of Letter. 
Unit <--RelatedTo--> Part <--RelatedTo--> Division <--RelatedTo--> Line <--RelatedTo--> Flat 
Eye <--RelatedTo--> Part <--RelatedTo--> Letter <--IsA-- Initial 