Response inquiry built-in functions are used to discover the characteristics of the stimulus that initiated a response. For example, if the response was stimulated by selecting an object, the value returned by the object function is the name of the object that was selected, and the values returned by the xcoord and ycoord functions are the position of the point selected in the object. If the response was stimulated by input from the keyboard or an application, the value returned by the input function is the data that was received by ESL from the keyboard or the application. These inquiries are shown in the following table.

These functions, like all other built-in functions, can be used directly, within a response definition, or indirectly, within an action routine called during the response.