It's less a theory these days than an exercise in controlling artes. Have you noticed that fonic artists always speak the incantation of whatever they're casting the same way each time? It's because the pitch is just as important as the incantation itself. How it's chanted dictates how the fonons are arranged and how the glyph links the caster to whatever they're using an arte on.

[That's a little convoluted though, so-]

Essentially, it's a targeting system.