Uncertainty modeling is a process that characterizes the sources of uncertainty, propagates the uncertainty through the analyses, and quantifies the effects of the uncertainty on the quantities of interest.

Computer-Aided-Design "Features that fit the end-user needs." (Hoffmann and Joan-Arinyo 1998; 321) [Hoffmann, C. M., & Joan-Arinyo, R. (1998). On user-defined features. Computer-Aided Design, 30(5), 321-332.]

Software "A user interface is a linkage between a human and a device or system that allows the human to interact with (e.g., exchange information with) that device or system." (Linux Information Project 2005; web) [The Linux Information Project. (2005). User Interface Definition. Retrieved from http://www.linfo.org/user_interface.html]