Must each letter in tefillin be completely surrounded by parchment and not touch another letter?

Synopsis

All authorities agree that each letter must be completely surrounded by parchment (hikuf gevil) and no letter may touch another. The Rema adds requirements for complete script (tamah), tagin (crown decorations), and writing with somewhat bold script.

Early Acharonim
Lenient
Strict
Lesser cited
Major authority

Discussion

Discussion coming soon.

The Daily Law

One question. Every opinion. Every morning.

A new halakhic question and the full spectrum of rabbinic thought, delivered daily.