10 UMLClass 250 100 160 100 STUDENT -- snumber ID first-name last-name degree bg=#dddddd Relation 400 120 270 50 lt=- m1=* r1= m2=* Buys > 10.0;20.0;250.0;20.0 UMLClass 460 140 140 30 when-purchased bg=#dddddd UMLClass 470 250 120 50 PURCHASE -- price-paid bg=#dddddd Relation 520 160 30 110 lt=. 10.0;90.0;10.0;10.0 UMLClass 650 100 170 100 BOOK -- ISBN ID title publisher authors[0..*] bg=#dddddd