Complex sentence: SME must ensure that any gmaps that it creates are structurally consistent; in other words, that they are one-to-one--such that no source maps to multiple targets and no target is mapped to multiple sources.
Split into simpler sentences: SME must ensure that any gmaps that it creates are structurally consistent. This means that they are one-to-one, such that no source maps to multiple targets and no target maps to multiple sources.