The SAFe 4.5 Large Solution SAFe defines the following item types: Solution Epic: Solution Epics are initiatives that are large enough to deserve analysis and a Lean Business Case but are reserved to a single Solution (Value Stream). Capability: Capabilities are similar to features, but account for higher-level behaviors of the solution. They often span multiple Agile Release Trains (ARTs). They are maintained in the value stream backlog and are sized to fit in a Program Increment (PI), so that each PI delivers solution value. Learning Milestone: Learning milestones mark specific progress points on the timeline and can be invaluable in measuring and monitoring the progress and risk of a program. PI Objective: Describes a specific goal with planned and assessed business value for Capabilities, Features or Stories delivered in a specified Program Increment or Iteration. The PI Objective can be at the program, team, or value stream level. Task: Defines a unit of work planned for a program increment and is estimated in hours. Defect: Defines a bug, error, or flaw in the solution. Risk: A risk is a potential event or future situation that could affect, prevent, or limit a project's success. Project risks might be seen as threats or opportunities. Retrospective: A Retrospective is an event to discuss what went well and what did not go well, and to define improvement for the upcoming period. Use a Retrospective work item type to ensure that this event occurs and to track the team's comments and plans.