​An assessment of a program's progress in implementing the Product Support Strategy, including the design and resultant Product Support Package to achieve the sustainment metrics consisting of the Sustainment Key Performance Parameter (KPP), Key System Attributes (KSAs), Additional Performance Attributes (APAs), and lower-level metrics that drive sustainment performance.  The SML concept includes twelve (12) levels spanning pre-Milestone A to Full Operational Capability (FOC).