1 Note This is a pre-print copy of a manuscript that has been submitted to the IEEE Transactions on Electromagnetic Compatibility for possible inclusion in a special issue on High Power Electromagnetic Fields. As it is currently undergoing peer review, it is possible that some aspects of this paper will change in the final version. D.V. Giri, Senior Member IEEE, and F. M. Tesche, Fellow IEEE Classification of Intentional Electromagnetic Environments (IEME)