Menu is a type of Agenda. Menu is related to Meal. Dish is part of Meal. Dish can be used for Eating. 
North is related to Main. Main is a different concept from Secondary. 
Agenda <--IsA-- Menu <--RelatedTo--> Meal <--PartOf-- Dish --UsedFor--> Eating 
North <--RelatedTo--> Main <--DistinctFrom--> Secondary 