As application semantics becomes more complex and dynamic in IT systems, it is necessary to engineer the application semantics in its own lifecycle of development parallel to system engineering. The application semiotics engineering process is under study as a methodology for engineering complex and dynamic business logic in intelligent applications. It stresses the informal specification, the traceability of engineering decisions and need of late-binding to a particular formal language representation and computational paradigm for distributed multidisciplinary collaborative modelling environment. The article describes how the application semiotics is developed in a lifecycle of iterative development.