Many taxonomies have emerged to assist managers in identifying common patterns among requirements and system types and then building on that knowledge to define and implement best practices and standards that are suited to particular categories of systems. Distinctions are made based on the function and role of the system, the types of risk to be addressed, the scale of systems and budgets, and other factors.

This report adopts the following taxonomy of IT programs:

1. Business systems and office IT

2. Command and control

3. Computing and communications infrastructure

4. Intelligence, Surveillance, and Reconnaissance (ISR), space, and weapons

The classification, which is loosely based on a classification scheme used within the DOD to track IT acquisition programs,¹ is primarily functional. But the functional categories also correspond roughly to distinctions among programs based on the extent of innovation (more in categories 2 and 4) and those that are more likely to have precedented requirements and architectures and thus build on established ecosystems (categories 1 and 3).

These categories also separate IT that is embedded in weapons or weapons systems or similar platforms with potentially high systems risk (category 4), IT in which software and hardware are less tightly integrated (categories 1 and 2), and IT that provides the computing and communications infrastructure (category 3) that can be used by systems identified in the other categories.

Because modern larger-scale systems are interconnected and therefore more often integrate across these functionalities, greater numbers of systems may cross these boundaries. For example, many weapons systems incorporate command-and-control functionalities.

Finally, despite the differences among these categories, most systems rely on similar development practices, including design and architectural concepts, programming languages, process and measurement concepts, and tools.