A Principle represents a qualitative statement of intent that should be met by the architecture.
Principles define intended properties of systems. A Principle defines a general property that applies to any system in a certain context. A Principle is motivated by some goal or driver. Organizational values, best practices, and design knowledge may be reflected and made applicable in terms of principles.
Motivation
"Systems should be customer facing", "Customers should have a great experience", "Colleagues should be informed", "Open Source Software should be used"