Direction is a type of Path. Path is related to Garden. Garden is related to Land. Land is related to Dirt. 
Bottom is a type of Supply. Bottom is a different concept from Top. Top is related to Tank. 
Direction --IsA--> Path <--RelatedTo--> Garden <--RelatedTo--> Land <--RelatedTo--> Dirt 
Supply <--IsA-- Bottom <--DistinctFrom--> Top <--RelatedTo--> Tank 