PDAW (personal digital assistant window) is a window system specially used in PDA (personal digital assistant). Its most outstanding characteristic is that it can support developing application program with adaptive user interface. Adaptive user interface has many different types. Because PDAW provides merely mechanism supporting adaptive but rule and status deciding adaptive strategy, it does not limit the type of adaptive user interface. PDAW consists of interface look, window kernel, device interface and programming interface. Mechanism supporting adaptive is implemented in the window kernel.