Definition
DoD 5000.02
DoD Instruction 5000.02 — the Adaptive Acquisition Framework governing US defense programs. Defines six acquisition pathways (Major Capability, Middle Tier, Urgent, Software, Services, Business Systems) with milestone reviews (MDD, Milestone A/B/C, FRP, IOC, FOC).
See this concept in action
Extant Portal implements mission engineering concepts as interactive tools.