WMLScript is a part of WAP application layer and it can be used to add client side functional logic. The WMLScript language is based on ECMAScript like JavaScript does. But it is modified to optimize to low bandwidth communication. WMLScript can empower WML, if they are used together. Also WMLScript can be used as standalone tool. [WMLSCRIPT]

Since WML, which is based on the XML, designed to specify content (such as images, text and selection list) for narrow banded devices, WMLScript can be the complementary part of it. WMLScript can do:
*Check the validity of user input
*Access to facilities of device. (eg. making a phone calls, send messages, etc)
*Generate messages and Dialog based on the logic thus it can avoid to communication roundtrip to server to show alert, error and confirmation messages.

These benefits of using WMLScript enables to have intelligence User Interface to device and to reduce total size of data between server and client.    


4.2	WMLScript, JavaScript, JScript, and Java
One of the difference between ECMAScript anf WMLScript is the fact that WMLScript has a defined bytecode and interpreter reference architecture. This architecture can optimize size of communication over narrow bandwidth architecture. Many of advanced ECMAScript features are dropped to make language to compile easily and to make smaller.   


[WMLSCRIPT] "Wireless Application Protocol WMLScript Language Specification ver 1.1", WAP Forum, 4-Nov.-1999.