Spellscribed Q&A: Meridians and Spellscribing

Nick Solomon asked:

Okay, so here's my questions: Did the Mercanians have the ability to shift their own meridians at will? And why doesn't spellscribing, which alters a user's meridians prevent one from casting other spells than those scribed upon the body?

Answer:
The Mercanians can manipulate their meridians, but it's not an 'at-will' thing. Such an action takes an effort of will and concentration on the spell they're focusing on. It would take more like hours to change their meridians.

Okay so there's more to meridians than just the surface. The meridians on the surface of 
the skin are more like 'veins' that cover the outside of the body. There are deep running meridians that are like 'arteries' that can channel more power than the meridians on the skin, but are pretty much impossible to manipulate because it's also the channels his life energy flows through. Those deep meridians are the ones that are instinctively tapped when spellcasting.