In Masechet Shabbat 104a, it talks about the shapes of the letters, and meaning behind it. One thing it says is: ומאי טעמא שיקרא אחדא כרעיה קאי ואמת מלבן לבוניה? And what is the reason that ...
If an Ashkenazi Sofer writes a Sefer Torah in the Sephardi or Yemenite tradition: a) has he fulfilled his obligation of writing a Sefer Torah (thanks, Double AA!), and b) since a Sefer Torah must be ...