Well, Charter magic is normal magic in the Old Kingdom. It's called that because it draws its power from the Charter.

[Discussing necromancy and Free magic- and that Sabriel is also a kind of necromancer- seems unwise after he's been through an already unsettling experience.

Especially in a wood that almost certainly isn't entirely normal.]

The Charter is... it contains and describes everything. Everything that is, that was, and that might be or could be again. By drawing on its power, and tracing the appropriate marks, mages can do magic.