A message about the error or warning which is device agnostic and readable by end users and application developers. It explains what the error or warning is, and how to fix it (in a general sense). If applicable, the value is localized to the end user's requested locale.
Contains a list of name/value pairs that provide additional information concerning this error or warning. Each item in the list is an input parameter that contributed to the error or warning condition.
See the Field Index to learn which calls use parameters.