Lower is related to Letter. Letter is related to Sign. Sign is related to Instructional. 
Mouse is a type of Manipulate. Mouse is related to Little. Little is related to Body. 
Lower <--RelatedTo--> Letter <--RelatedTo--> Sign <--RelatedTo--> Instructional 
Manipulate <--IsA-- Mouse <--RelatedTo--> Little <--RelatedTo--> Body 