Ashuri alphabet means Assyrian alphabet and also refers to the Assyrian script

Assyrian script

Assyrian script may refer to:*The traditional name for the Hebrew alphabet*The Eastern variant of the Syriac alphabet*Cuneiform, a writing system used for the extinct Akkadian language...

 (Hebrew: k'tav ashuri) which is a traditional name for the Hebrew alphabet

Hebrew alphabet

The Hebrew alphabet , known variously by scholars as the Jewish script, square script, block script, or more historically, the Assyrian script, is used in the writing of the Hebrew language, as well as other Jewish languages, most notably Yiddish, Ladino, and Judeo-Arabic. There have been two...

 and a term that was first used in the Mishnah

Mishnah

The Mishnah or Mishna is the first major written redaction of the Jewish oral traditions called the "Oral Torah". It is also the first major work of Rabbinic Judaism. It was redacted c...

 to refer to either the Aramaic alphabet

Aramaic alphabet

The Aramaic alphabet is adapted from the Phoenician alphabet and became distinctive from it by the 8th century BC. The letters all represent consonants, some of which are matres lectionis, which also indicate long vowels....

 or the formal script used in certain Jewish ceremonial items, including Sefer Torah

Sefer Torah

A Sefer Torah of Torah” or “Torah scroll”) is a handwritten copy of the Torah or Pentateuch, the holiest book within Judaism. It must meet extremely strict standards of production. The Torah scroll is mainly used in the ritual of Torah reading during Jewish services...

, Mezuzah

Mezuzah

A mezuzah is usually a metal or wooden rectangular object that is fastened to a doorpost of a Jewish house. Inside it is a piece of parchment inscribed with specified Hebrew verses from the Torah...

, Tefillin

Tefillin

Tefillin also called phylacteries are a set of small black leather boxes containing scrolls of parchment inscribed with verses from the Torah, which are worn by observant Jews during weekday morning prayers. Although "tefillin" is technically the plural form , it is loosely used as a singular as...

 also abbreviated as STA"M (Hebrew: סת"ם). It is also referred to as the “square” script.

There are many rules concerning the proper formation of letters if the written text is to be valid for religious purposes.

The Ashkenaz, Sefard, Chabad

Chabad

Chabad or Chabad-Lubavitch is a major branch of Hasidic Judaism.Chabad may also refer to:*Chabad-Strashelye, a defunct branch of the Chabad school of Hasidic Judaism*Chabad-Kapust or Kapust, a defunct branch of the Chabad school of Hasidic Judaism...

 (Lubavitch), and Am Mizrachi (Iraqi Jews) each have their own calligraphic tradition in the method by which each letter is formed, however the final shape of each letter conforms to the legal standard regardless of the calligrapher. While the shapes of the letters are the same, styles can be quite different. Generally, while each tradition favors their own calligraphic style as preferable, none consider the tradition of the other passul (invalid) for Sifrei Torah (Torah scrolls) or any other ritually used scroll or parchment.