HISTORY lines and the CC BY 2.0

[Orion Pobursky]

Since I (as PTadmin) am giving you direction to edit, you can edit.

That said, don't add a !HISTORY line unless:
a.) You're sure it's needed
b.) It's not an edit by myself, Chris, or Steve (we're already covered by PTadmin)
c.) It's clear what the edit was.

After some thought I'll also add:
If the edit was in the header only. The header is touched by both admin and PT software. As such, those edits are covered by the PTadmin attribution.