I am wondering what is the opinion on Shu"A Ha'Rav? Does he agree with the Mishna Berurah that the insides of letters (at least 3-walled letters) are exempt from the requirement of hekef gvil (at least after the fact)? Or does he hold that the inside is no different than the outside?
From my learning I have concluded that the inside is no less than the outside.
I'm wondering if anyone understands differently?