Index is a type of Supply. Index is a type of Scale. Scale is related to System. you are likely to find System in/at/on Shop. 
Stimulus is related to Sound. Drum is a type of Sound. Drum is related to Beat. 
Supply <--IsA-- Index --IsA--> Scale <--RelatedTo--> System --AtLocation--> Shop 
Stimulus <--RelatedTo--> Sound <--IsA-- Drum <--RelatedTo--> Beat 