Common use of Transitional Clause in Contracts

Transitional. We could instead use any XML language that can be described by DSD2 or DTD, for example WML if we want to apply the contract framework to WAP service development instead. Using the DSD2 language has the benefit that it allows more syntactic requirements to be formally captured than DTD or even XML Schema. For example, the DSD2 description of XHTML expresses the facts that form elements cannot be nested, that input elements must have a name attribute unless the value of type is submit or reset, and that the values of color attributes must be valid color descriptions. The full DSD2 schema is available at xxxx://xxx.xxxxx.xx/DSD/xxxx0-xxxxxxxxxxxx.xxx. The templates shown in the example in Section 4.1 can be seen to fulfill the designer obligations induced by the contract in Figure 2. It is generally far from trivial to verify that the validity requirement is satisfied; in Section 5.2 we present an automatic and conservatively approximating approach.