as: Error

 
 7.31 '.error "STRING"'
 ======================
 
 Similarly to '.err', this directive emits an error, but you can specify
 a string that will be emitted as the error message.  If you don't
 specify the message, it defaults to '".error directive invoked in source
 file"'.  SeeError and Warning Messages Errors.
 
       .error "This code has not been assembled and tested."