Natural language user interfaces are expected to be useful and provide a friendly atmosphere for human users working with intelligent human-computer interaction systems. Building correct and consistent large-scale script data for such interfaces requires large costs for construction and maintenance. Scripts written by many end-users in thoroughly flexible script languages might be a practical solution to this problem. We propose a dialog script description language and its framework. Two versions of script execution engines have been developed in C++ and Erlang programming languages. An example dialog script processed by one of these engines shows that a script editing function can be successfully represented by the script language. Because the script language has self-extending flexibility and ability to represent several versions of scripting languages, it increases the opportunity for end-users to accumulate and share a large amount of script data.