Many functions detect errors. The description of such functions will include these error conditions and suggested formats for display of the generated error messages. A call on the ERROR function is implied but the error number is not specified by Standard LISP. In some cases a warning message is sufficient. To distinguish between errors and warnings, errors are prefixed with five asterisks and warnings with only three.
Primitive functions check arguments that must be of a certain primitive type for being of that type and display an error message if the argument is not correct. The type mismatch error always takes the form:
***** PARAMETER not TYPE for FN
Here PARAMETER is the unacceptable actual parameter, TYPE is the type that PARAMETER was supposed to be. FN is the name of the function that detected the error.