and managed to write two letters, he is liable. The Talmud asks: Didn’t we learn in the Mishnah that one is exempt in that case? The Talmud answers: This is not difficult: That case where we learned that he is exempt is referring to a case where the letters require crowns. This is referring to a case where they do not require crowns, and he is liable. If the letters already had their requisite ornamentation and an individual separated them, it is as if he wrote two letters.
כתב אות אחת נוטריקון, רבי יהושע בן בתירה מחייב וחכמים פוטרין. אמר רבי יוחנן משום רבי יוסי בן זימרא: מנין ללשון נוטריקון מן התורה, שנאמר: ״כי אב המון גוים נתתיך״ — אב נתתיך לאומות, בחור נתתיך באומות, המון חביב נתתיך באומות, מלך נתתיך לאומות, ותיק נתתיך באומות, נאמן נתתיך לאומות.
We learned in the Mishnah If one wrote one letter as an abbreviation [notarikon] representing an entire word, R' Yehoshua ben Beteira deems him liable to bring a sin-offering, and the Rabbis deem him exempt. R' Yoḥanan said in the name of R' Yosei ben Zimra: From where is it derived that the language of abbreviation is employed in the Torah? As it is stated: “Neither should your name any more be called Abram, but your name should be Abraham; for the father of a multitude of nations [av hamon goyim] have I made you” (Genesis 17:5). The verse itself contracts av hamon into Abraham [Avraham]. The words av hamon themselves are interpreted as an abbreviation: I have made you a father [av] for the nations, I have made you chosen [baḥur] among the nations, I have made you beloved [ḥaviv] among the nations, I have made you king [melekh] for the nations, I have made you distinguished [vatik] for the nations, I have made you trusted [ne’eman] for the nations.