What is the difference between the various styles of script used in Stam today-Kesav Beis Yosef, Arizal:
All scripts are Kosher if they maintain the legal form of the letter:
Initially, the letters of the script must be written whole and complete, following the form of letters that were taught in the Talmud, Midrashim, and in tradition from the Rishonim. [see B for the exact sources] However, if one swerved from this and wrote the form or script of the letter differently than the above tradition, then so long as it still retains its correct letter form, it is valid. [The explanation of this is as follows: Just as in the English language there are various fonts and typefaces in which letters can be written in, as can be readily seen in every word processor document, so too in the Hebrew language there exists various fonts and typefaces in writing the letters. The common denominator of all scripts and typefaces is that they retain the same general shape of the letter, and their differences are only in minor nuances of how that general shape is written. The novelty of the above ruling is that according to tradition, aside for the general shape that every letter contains as is well known, the letters also contain a very specific form and shape with various nuances which are only taught from one scribe to another. Nonetheless, some of these nuances of the script are not invalidating details and hence the letters can be valid even if they were not written like the above tradition so long as they retain the identifiable shape of the letter. Indeed, for this reason, the Rambam does not mention at all how to write the letters, and we find a change in style from generation to generation and country to country, including styles that were innovated later on in time. In his Shulchan Aruch chapter 36, the Alter Rebbe goes through each and every letter of the Hebrew alphabet and explains how it is to initially be written, what invalidating details apply to it, and what details are not essential and would therefore deem the letter valid even if missing, even though initially it is to be written, as stated above.]
Example of invalidation: Any letter that was miswritten as another letter, such as if a Reish was written as a Daled, or Beis was miswritten as a Chaf, then the Tefillin is invalid.
The sources for how to write the letters of the traditional script:
Interestingly, while some details of the letters can be found scattered in the Talmud Midrashim and early Rishonim, for the most part they are not recorded in detail in the above works. Seemingly, either the details that we follow today were handed down by oral tradition to the Sofrim of each generation, or they had the flexibility to write the letters as they saw fit, so long as they conformed to the recorded details of the Rishonim and Talmud. The first most complete compilation on the subject of the form of the letters is the Sefer “Baruch Sheamar-Alfa Beisa,” which was written in the 1400s by Rabbi Yom Tov Milhozen, and quoted in detail by the Beis Yosef in chapter 36. [In the Shulchan Aruch, however, he does not write the form of the letters.] The Alfa Beisa goes through each letter in 4 different versions, bringing the traditions from his predecessors, the Rishonim [although the Beis Yosef only lists two of these versions]. Following the precedent of the Alfa Beisa, and Beis Yosef, the Alter Rebbe in his Shulchan Aruch chapter 36 lists in detail each letter and it’s nuances of writing, including in it all the main opinions until his day, as well as the opinion of the Arizal according to Kabbalah. While including this in a formal Halachic work of Shulchan Aruch was the novelty of the Alter Rebbe, after his time, other authors have also compiled such works, detailing the nuances of each letter, including the Keses Hasofer of the Baal Hakitzur Shulchan Aruch in chapter 5:2, and the Mishneh Berurah on chapter 36 in his Kuntrus Mishnas Sofrim. Other more detailed works have been written today, such as the Sefer “Mishmeres Stam-Tzuras Haosiyos.” Nonetheless, the above works are not in place of learning how to write the letters in their detail from an actual expert scribe. In the words of the Shaareiy Teshuvah: “G-d fearing men are to learn them Ish Mepi Ish, by choosing an expert scribe and reviewing with him each letter, having him specifically point out what is correct. This comes to negate those who look at books and write based on what they read, as while they think they’re doing it correctly in truth they are diverting from the true intent.” Now, this does not mean that all the Jewish people conform to one font and script based on the above works and traditions from Sofer to Sofer, as indeed we find traditions that swerve from that which is explained in the above books, as well as differences in the font of the writing. The Alter Rebbe himself innovated a new script/font, as will be explained in Halacha 7, which incorporates many of the rulings of Kabballah. We will now focus on the various scripts that are written today.
The four fonts/styles of scribal script- Beis Yosef; Vallish; Arizal; Admur Hazakein:
The Rosh testifies that the fonts of the letters defer from country to country, and that they are all valid so long as they conform to the basic Halachic requirements of the components of the letters. Today, there exists four fonts for writing of scribal letters that are available on the market:
- Kesav Beis Yosef [Ashkenazim]
- Kesav Velish [Sephardim]
- Kesav Arizal [Chassidim and some Chabad]
- Kesav Hameyuchas of Admur Hazakein. [Some Chabad]
Kesav Beis Yosef-Ashkenazi: The first original, and once most prolific, font for writing the scribal letters was Kesav Beis Yosef, following the opinion of Rav Yosef Karo, based on the Rishonim. This script is still used to this very day by Ashkenazi Jewry for all their Stam products and is hence also referred to as Kesav Ashkenazi. [Although this form of writing is named after the Beis Yosef, ironically it is not followed by the Sephardim today, but rather only by the Lithuanian Ashkenazim.]
Kesav Velish-Sephardi: The second known script which was commonly used was Kesav Vallish. This font is the script which is used by Sephardim all over the world until this very day, for all their Stam products, and is hence also referred to as Kesav Sephardi. [This script is not recorded in the Rishonim, and there is no clear tradition regarding the particular components of each letter.]
Kesav Arizal-Chassidic: The third form of script is known as Kesav Arizal, which is basically a similar font to that of Kesav Beis Yosef, but incorporates certain important Kabalistic nuances. These nuances are found in only specific letters, mainly the Alef, Vav, Ayin, Tzaddik, and Shin. [It is named after the Arizal being that he is the one who authored these changes. Although ideally the changes of the Arizal were only in the above said letters, today’s Arizal script follows the form of letters innovated by Rav Nesanel Topilansky, a Jerusalem scribe, who in turn learned it from a scribe from Minsk, who in turn learned it from the Parshiyos of the Gr”a. This form of script of Arizal differs from the form that was written in Europe prior to the Holocaust. ]
Kesav Alter Rebbe: See here
 See Tur and Shulchan Aruch Admur chapter 36; See Sefer Tzidkas Hatzadik of Rav Aryeh Leib Friedman; Sefer Osiyos Harav [Rav Moshe Viner]; Sefer Ketav Chabad [Avraham Levi-2009]; Sefer “Mishmeres Stam-Tzuras Haosiyos
 Admur 36:1; Michaber and Rama 36:1; Sefer Baruch Sheamar, brought in Beis Yosef 36
 Admur ibid; Rosh ibid; Noda Beyehuda Tinyana Y.D. 171; See Shut Harosh 3:1 that the fonts of the letters defer from country to country, and that they are all valid so long as they conform to the basic Halachic requirements of the components of the letters; The Rambam in his Magnum Opus Mishneh Torah does not mention even one detail regarding the form of the letters, it does not even quote the rulings of the Rif or statements of the Talmud brought above and simply writes that letters that don’t have the form that a child can read are invalid, thus proving as above.; Sefer Osiyos Harav ]Rav Moshe Viner] p. 3
Writing the head and tail of each letter: See Piskeiy Teshuvos 32:7
How to write the Yud-Making the Kotz of the Yud: See Piskeiy Teshuvos 32:46
 See Admur 32:23; 36:1; Michaber 36:1; M”B 143:25; See Piskeiy Teshuvos 32:7; 143:13-8
 See Sefer Tzidkas Hatzadik of Rav Aryeh Leib Friedman and the introduction of Sefer Osiyos Harav ]Rav Moshe Viner] p. 3 for a thorough analysis on the original sources of the forms of the letters
 See Shabbos 103b-104a for Agadata on various letters [This Braisa is the 1st and most primary source for the letters, as ruled by the Rishonim]; Menachos 29; Yerushalmi Midrash Al Tag Habeis
 Midrash Raba; Midrash Osiyos Rebbe Akiva; Sefer Hazohar
 See Tur 36; Rosh Sefer Torah 12; Orchos Chaim 25; Rashba 7:352; Sefer Hateruma; Hagahos Maimanis; Sefer Baruch Sheamar-Tikkun Tefillin of Rebbe Shimshon; Sefer Haiggur; Sefer Hatemuna; Sources in Beis Yosef 36:1; Sefer Baruch Sheamar-Alfa Beisa records many traditions in the name of the Rokeiach, Ort Zarua, and Rabbeinu Yehuda Hachassid; Rav Yehuda Hachassid wrote a Sefer Kisrei Osiyos which includes many of his traditions of the letters [This Sefer was recently published in Koveitz Sifrei Stam by Rav M.M. Meshi Zahav, 1970]; Interestingly the Rambam in his Magnum Opus Mishneh Torah does not mention even one detail regarding the form of the letters, it does not even quote the rulings of the Rif or statements of the Talmud brought above and simply writes that letters that don’t have the form that a child can read are invalid; For the most part, one can conclude that it was mainly Ashkenazi Rishonim who bothered to document their traditions of the form of the letters in contrast to the Sephardic Rishonim who in general did not do so; See Osiyos Harav ]Rav Moshe Viner] p. 4
 As writes Rabbi Shimshon in his introduction to his Sefer Baruch Sheamar, that it was for this reason that the Rambam did not bother writing the form of the letters as it was well known to all.
 See Sefer Osiyos Harav [Rav Moshe Viner] p. 4
 Lots of confusion surrounds the author and exact timing of the writing of this work, and in general it is really split to three sections, each now being claimed to have been written by a different author, but receiving the general title of Baruch Sheamar by the Beis Yosef and others. [See Introduction to Sefer Kovetz Sifrei Stam by M.M. Meshi Zahav]
 See Sefer Osiyos Harav [Rav Moshe Viner] p. 8-9 where he explains the general intent of the Alter Rebbe in his Shulchan Aruch and goes through a full commentary on every single letter brought by him
 It was omitted from the Rambam, Tur and Shulchan Aruch of the Michaber
 The work of the Keses Hasofer is almost a verbatim quote the Alter Rebbe’s chapter 36, while the Kuntrus of the Mishneh Berurah follows the wording of the Beis Yosef and Baruch Sheamar.
 For a full analysis on this subject refer to the Sefer Tzidkas Hatzadik of Rav Aryeh Leib Friedman and the Sefer “Inside Stam” [Rabbi Reuvain Mendlowitz; Feldheim] Chapter 3
 Shut Harosh 3:1; See Ledavid Emes 13 in name of Shaar Hakavanos Tefillin 2 that they are all from Moshe; Maharsham 2:120 in name of Matzas Shmurim; Os Chaim Veshalom 36:2; Igros Moshe 5:2; Piskeiy Teshuvos 36:1
Other opinions: Some Poskim rule that a Sephardi is not Yotzei with the script of an Ashkenazi. [Maharam Chaviv Kol Gadol 78, brought in Shaareiy Teshuvah 36:1 in name of Birkeiy Yosef; See Piskeiy Teshuvos ibid footnote 2]
 See Beis Yosef O.C. 36 who only records these letters “Know, I have found a Kuntres of a later Acharon whose name is Yitzchak Barcuh Sheamar, who speaks of the forms of the letters, and it has found favor in my eyes, and therefore I felt that its befitting to record it here.” ; The origin of these letters is from the Sefer Baruch Sheamar, and other Rishonim
 See Yaavetz in Mur Uketzia 36; Chida in Ledavid Emes 13:3
 The difference between Kesav Arizal and that of Kesav Beis Yosef is that it incorporates many of the nuances required according to Kabbalah to be in the fonts, in contrast to Kesav Beis Yosef or Ashkenazi which follows the nuances required based on Halacha.
 See Admur 36:2 under the letter Tzadi that its Yud is written upside down; Mishnas Chassidim Tikkun Tefillin 1:10; Matzas Shmurim 31; Mishnas Avraham 23:86-88; Miasef Lekol Hamachanos 36; See Igros Kodesh 3:436, printed in Shulchan Menachem 5:203, in defense of this; See Sefer “Inside Stam” chapter 3 for the great controversy over how to write the Tzadik, and the opinions of the Lithuanian Gedolim on this matter. See Sefer Tzidkas Hatzadik of Rav Aryeh Leib Friedman for the defense of writing the Tzadi with the upside down Yud. See the many Poskim mentioned in Piskeiy Teshuvos 36 footnote 5 who all defend the validity of the upside Tzadik according to all opinions including Ashkenazim, including: Igros Moshe O.C. 8:2; Rav SZ”A in Halichos Shlomo 4:22; Minchas Yitzchak 4:47; Shevet Halevi 10:7; Yabia Omer 9:108
 See Admur 36:2 under the above letters for the tradition of the Arizal in how to write them, versus the tradition of the previous Poskim
 See Sefer Kesiva Tama