Old is related to Century. Century is related to Marker. Marker is related to Standard. Norm is a type of Standard. 
Home is related to Unit. Unit is related to Small. Small is related to Rat. 
Old <--RelatedTo--> Century <--RelatedTo--> Marker <--RelatedTo--> Standard <--IsA-- Norm 
Home <--RelatedTo--> Unit <--RelatedTo--> Small <--RelatedTo--> Rat 