What is a "friendly" secession as opposed to a "strategic" secession?

[Sarwell]

The "Rules and Policies" say that the latter is prohibited, but the former is acceptable. Which brings me to this question: what constitutes a "friendly" secession, and what makes it similar enough to a "strategic" one that the difference on how they are treated must be specified?

[Geronus]

The "Rules and Policies" say that the latter is prohibited, but the former is acceptable. Which brings me to this question: what constitutes a "friendly" secession, and what makes it similar enough to a "strategic" one that the difference on how they are treated must be specified?

A friendly secession is one in which the seceding Duke and the government of the original realm have jointly planned the secession to purposely create a new realm.

A strategic secession is a friendly secession that is undertaken for the express purpose of creating a strategic advantage during a war by creating a new capital that is closer to the front lines. It is forbidden for the same reason that strategic capital moves are forbidden.