When you’re building a spellcaster, the powers are often similar regardless of the type of caster—the configuration of them is where the variety comes in. Your main focus will be on configuring these powers to give your caster his specific identity. Along with these powers comes the opportunity to choose various specializations and to create items and rotes.
If you absolutely must have a specific rule, try this one from the "Building a Practitioner" sidebar (my emphasis):I love the PDF that came with the book; it makes finding stuff like this ... well, possible in a way that the hard copy doesn't.
I love the PDF that came with the book; it makes finding stuff like this ... well, possible in a way that the hard copy doesn't.