Upon identification of information exchange requirements, the process of mapping data elements to NIEM requires developers to search through the model to identify semantic equivalent elements between an organization's data set and the NIEM model. There are a number of ways to explore the model to aid this process: the Data Model Browser; several alternate model formats, such as spreadsheets and a database; the Subset Schema Generation Tool (SSGT); and third party toolsets.
The NIEM architecture consists of two sets of vocabularies-NIEM Core and the individual NIEM domains. NIEM Core includes "universal" components, concepts that are commonly understood across all (or the majority of) NIEM domains, such as person, activity, date, time, and location. The individual NIEM domains contain mission-specific data components that build upon concepts in NIEM Core.
The current NIEM release can be found here.