Article from Ed Seidewitz / InteliData Technologies Corporation. Over the years since the adoption of the first UML and MOF specifications, there has been a great deal of discussion within the OMG community on modeling and metamodeling and the relationship of modeling and metamodeling languages. In order to address this topic as clearly as possible, I asked myself a series of questions that, I think, need to be answered together to understand the fundamental question of “What do models mean?” This paper gives my answers to my own questions.