With the advent of multitier and service-oriented architectures, the presentation tier is more detached from the rest of the web application than ever. Moreover, complex web applications can have thousands of linked web pages built using different technologies. As a result, the description of navigation maps has become more complex in recent years. This paper presents NMMp, a UML extension that: (i) provides an abstract vision of the navigation structure of the presentation tier of web applications, independently of architectural details or programming languages; (ii) can be automatically transformed into UML-WAE class diagrams, which can be easily integrated with the design of the other tiers of the web application; (iii) encourages the use of architectural and multitier design patterns; and (iv) has been developed according to OMG standards, thus facilitating its use with general purpose UML CASE tools in industry.