FAQ re: Principle 2.1
Question: What is the sense of "behavior" in Manifesto principle 2.1?

Rules are explicit constraints on behavior and/or provide support to behavior.

The sense of "behavior" is how the business and the people involved in its activity behave - i.e., act (or react), perform or function. Activity that is automated should be viewed simply as extensions of business behavior; that is, rules also apply.

FAQ re: Principle 2.3
Question: What does Manifesto mean by "relevant" in principle 2.3?

Rules apply across processes and procedures. There should be one cohesive body of rules, enforced consistently across all relevant areas of business activity.

"Relevant" means "within scope". The Manifesto does not require that scope be the entire enterprise; it might be a single business area, business capability, or line of business. Also, Manifesto does not require that the scope be limited by the boundaries of a single enterprise (e.g., as in supply chains, regulated businesses, rule adoption, etc.)

References:

[1] The Manifesto is free, only 2 pages long, translated into 15 languages. Have a quick look (or re-look!). No sign up required. Well worth your time.