Asemic writing is writing down non-existent characters. 

To me asemic writing is a calming exercise for my brain as well as my mind. I give my hands the opportunity to let go of the controlling system of my will. 

Practising keeping an asemic journal is a way to letting steam of emotions. Asemic diaries need no lock!

Also new formed letters give me joy with their surprising beauty. Sometimes I use them to practise calligraphy, I call them callisemics https://callisemics.blogspot.com/

Asemics are very intriguing. I follow some practitioners on Insta. Especially their little movies often take my breath away. 

Recently I took up asemic embroidery, it's so much fun.

In short, asemics, highly recommended!

My definition of asemic writing: Everything that could be written

(i.e. it is possible to write it, and it is possible that something that already exists might have been created through writing).

I believe the first time I heard of it was in Rosaire Appel's artist book Math Minus Math. It uses mathematical notation, but with complete disregard for the signs' meaning. Vera Molnar wrote computer programs to simulate her mother's handwriting. It can be spontaneous, unsystematic doodles, but I think one might also invent a set of letter-like signs and use them in some random, non-signifying order. Not necessarily left-to-right, top-to-bottom.

It's a pity the qwerty keyboard isn't configured for asemic writing! Maybe if you unwittingly switch to Dvorak and make some automatic substitutions to obscure Unicode characters?