SAFe refers to the Scaled Agile Framework. According to the Scaled Agile Framework website (http://scaledagileframework.com/):
The Scaled Agile Framework is a proven knowledge base for implementing agile practices at enterprise scale. Its primary user interface is a “Big Picture” graphic which highlights the individual roles, teams, activities and artifacts necessary to scale agile from the team, to teams of teams, to the enterprise level.
The Big Picture describes three levels of scale:
Team, Program and Portfolio. Each of these scales the essential agile elements of Value (requirements and backlogs) Teams (from development team through portfolio) and Timebox (iteration, PSI, budget cycle). This model of agile adoption has been elaborated primarily in Dean Leffingwell’s books Agile Software Requirements: Lean Requirements for Teams Programs and the Enterprise (2011) and Scaling Software Agility: Best Practices for Large Enterprises, (2007) and his scalingsoftwareagility blog.
Leffingwell, Dean (2011).
Agile Software Requirements, Lean Requirements Practices for Teams, Programs, and the Enterprise,
Addison-Wesley Professional, ISBN 978-0321635846.
Leffingwell, Dean (2007).
Scaling Software Agility, Best Practices for Large Enterprises,
Addison-Wesley Professional, ISBN 978-0321458193.