Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. NIEM is a reference model. This means it is not a rigid standard that must be used exactly as it is in its entirety. NIEM was designed as a core set of building blocks that are used as a consistent baseline for creating exchange documents and transactions across government. While an XML Schema rendering of the entire model exists, it is not a requirement for NIEM conformance that this entire schema be used for validation. Nonetheless, there are several informal conformance requirements. The goal of NIEM conformance is for the sender and receiver of information to share a common, unambiguous understanding of the meaning of that information. Conformance to NIEM ensures that a basic core set of information (the NIEM components) is well understood and carries the same consistent meaning across various communities. The result enables a level of interoperability to occur that would be unachievable with the proliferation of custom schemas and dictionaries.