10.1 Forward Contracts10.2 Options10.2.1 Longs, Shorts, Calls, and Puts: Representing a Tricky Vocabulary10.2.2 To Subtype or Not to Subtype10.3 Product10.3.1 Should a Product Always Be There?10.4 Subtype State Machines10.4.1 Ensuring Conformance of State Charts10.4.2 The Problems with Using Conformance10.5 Parallel Application and Domain Hierarchies10.5.1 Type Checking in the Application Facade10.5.2 Giving the Supertype an Encompassing Interface10.5.3 Using a Run-Time Attribute10.5.4 Making the Application Facade Visible to the Domain Model10.5.5 Using Exception HandlingReferences