Does the Biblical prohibition against writing on Shabbat apply to nonsense as well?

Question

Writing (כותב) is one of the 39 melachot (forbidden labors) of Shabbat.

Writing nonsense is forbidden regardless, but i'm curious whether it's a Biblical or Rabbinic prohibition.

On a Biblical level, must the writing make sense to qualify as koteiv? Or can it simply be any random markings?

Nonsense here is defined as both "isdhbihdagidgfyiwiyda" and random squiggles/doodling.

Answer 1

Shulchan Aruch Harav Orach Chaim 278.1

...אין איסור מן התורה אלא במלאכה הצריכה לגופה...

...it is not oser from the torah unless it is a labor that is needed... (my translation)

So it seems that if you so do not need the markings it is not a Biblical prohibition.

Shulchan Aruch Harav Orach Chaim 340.8

...כל שהוא תבנית איזה כתב אפילו אינו אשורי ואפילו אינן אותיות ידועות אלא שרגילין לסימן בעלמא כגון הסימנים שרגילין לעשות בהם המספר הרי זה נקרא תבנית כתב וחייב עליו אם עשאו בדבר המתקיים... כל כתב מאיזו אומה שלא גמר אותיותיו כתיקונן פטור עליו ...

...everything that is the marking of a letter in some writing, even not Ashuri (Hebrew of a scribe) even it is not known letters only that it is used as a sign i.e. signs that are usually used to symbolize numbers, it is considered writing and is hayav (Biblicaly liable) for them if he make them to last (written with something that lasts on something that lasts)... all writing in all languages that you did not complete the letters as they should be you are potur (not Biblicaly liable)... (my translation)

Shulchan Aruch Harav Orach Chaim 340.5

המגיה אות אחת כגון שנטל לגגו של חי"ת ונעשו שני זייני"ן חייב (והמגיה אות אחת אחרת כגון שנטל לגגו של ד' ועשאו ר' פטור אבל אסור מן התורה)

One who fixes a letter by removing the roof of the letter ח (in Ashuri (Hebrew of a scribe) (see link the 5th from the right)) and by doing so 2 זs were made is hayav (Biblicaly liable), and the one who fixes a letter by removing and making a ד into a ר is potur (not Biblicaly liable) but it is a Biblical prohibition (my quick translation)

So it seems that the writing need not make sense to qualify as koteiv on a Biblical level.

Shulchan Aruch Harav Orach Chaim 340.7

... אם אינו תבנית כתב ואינו רושם אלא לסימן בעלמא ולא כמין אותיות מותר אפילו לכתחלה ... ויש ... שסוברים שאפילו הרושם לסימן בעלמא ולא כתבנית כתב חייב ... וירא שמים יחמיר לעצמו כדבריהם ...

(opinion accepted to law).. if it is not writing only as a mark not as letters, it is ok even lihatchila (if will be lasting -- oser dirabonon)... and there are that hold that even a mark for a just for a sign (not letters) is hayav (Biblicaly liable) ... a G-d fearer should be strict on himself and act according to their (the second) opinion... (my translation)

So it seems that by law we go according to the option that squiggles/doodling do not qualify as koteiv on a Biblical level.

PS: One letter is also a Biblical prohibition.

Shulchan Aruch Harav Orach Chaim 340.4

על אות אחת פטור אבל אסור מן התורה כשאר חצי שיעור

For one letter you are potur (not Biblicaly liable), but it is a Biblical prohibition, as is the law by the rest of "hetsi shiur" (my translation)