This is used to iterate over all the error-packaging objects. Within the tag, the special variable $error is made available within the opening and closing tags. This variable can then be used to output those things which an error report should have.
At the time of this draft, the only real requirement to be a MIC-compliant error-packaging object are those methods necessary to create and iterate. For this reason, one must look to the documentation for the error packaging object to figure out how to do what one wants. Later versions of MIC will likely have a more integrated and user friendly interface.