ESL's predefined built-in inquiry functions allow you to inquire about the attributes of an object or the nature of a stimulus. For example, you might use a function to find the current position of an object's graphics cursor, or to determine the specific text of an input that triggered a response from the keyboard. As the answer to your inquiry, ESL returns a value for the function, based upon the position or contents of the object, or the nature of the stimulus.
All built-in function names are keywords and therefore begin with lowercase letters. Since built-in functions return values, they can be used anywhere a value of the appropriate data type is expected, such as in expressions and object definitions.
The following gives you an overview of all the built-in functions. All the functions are described in detail in the Reference Guide.
There are five categories of built-in functions:
| Type of Built-in Function | Use To: | 
| Object | Inquire about the characteristics of a particular object. | 
| Item | Inquire about the characteristics of action bar items. | 
| Action | Determine whether certain textual region statements were executed successfully. | 
| Response | Inquire about the characteristics of a stimulus that produced a response. | 
| Special | Make special inquiries, such as determining the current time or the amount of free memory. |