Overload a built-in function

The database server provides functions that handle the built-in data types. You can write a new version of a built-in function that allows the function to operate on your new data type. If you write a new version of a built-in function, follow these rules:

• The function must be one that you can overload, as listed in Built-in functions that you can overload. The name is not case sensitive; the abs() function is the same as the Abs() function.
• The function must handle the correct number of parameters, and these parameters must be the correct data type.
• The function must return the correct data type, where appropriate.