ESL's predefined built-in functions allow you to inquire about the attributes of an object or item, or the nature of a stimulus during execution. As the answer to your inquiry, ESL returns a value for the function, based upon the position or contents of the object or item, or the nature of the stimulus.

All built-in function names are keywords and, therefore, begin with lowercase letters. You can use built-in functions anywhere a value of the appropriate data type is expected.

There are five types of built-in functions, as follows:

Action Inquiry functions allow you to determine the success or failure of certain statements related to textual regions.

Item Inquiry functions allow you to inquire about the characteristics of a specified item.

Object Inquiry functions allow you to inquire about the characteristics of a specified object. Object inquiry functions that require internal calculations (xsize, ysize, column size, and line size) will not return the correct value when used in the definition of a compile-time object. (These calculations are not made until runtime.) Note that menu items are not objects, so these functions do not apply to them.

For those object inquiry functions that are followed by the optional keyword of, you can omit the object name when the function is specified in a drawing statement. In this case, the object defaults to the current object. If you try to specify any of these functions without an object name in any statement other than a drawing statement, ESL generates an error message. Always specify the object name for the function, even if the syntax allows you to omit it.

Response Inquiry functions allow you to inquire about the characteristics of the stimulus that initiated a response.

Special Inquiry functions allow you to inquire about various things, such as the current time or date, or the number of characters in a string variable.

Following are tables containing brief descriptions of each ESL built-in function within each of these categories.