431. The Special Letters and Crowns
Tefillin, Mezuzah v’Sefer Torah 7:8
One must be careful with the oversized letters, the undersized letters, the letters with dots, the letters with unusual shapes like the bent letters pei, and the crooked letters. The scribes have copied these from their predecessors in an unbroken tradition. Care must likewise be taken with the crowns and the number of crowns on a given letter. Some letters have one crown, others have as many as seven. These crowns are shaped like the letter zayin; they are written as thin as a hair.
Tefillin, Mezuzah v’Sefer Torah 7:9
The above details reflect the optimum way to write a sefer Torah. If one is imprecise with the placement of the crowns, the Torah is still valid so long as all the letters are written properly. Similarly, if the lines are too close together, too far apart, longer than they should be, or shorter than they should be, the scroll is still valid so long as one letter does not touch another, no letters are missing, no surplus letters are added, the shape of no letter is changed, and the form of the “open” and “closed” sections is not changed.