I think plain writing is just what you think it is or to me I would say not joined up and how you see it on computers like the font Ariel.
Hope this helps
Plain writing is a writing style that conveys information clearly and concisely, using simple language without unnecessary jargon or complexity. It aims to make the text easily understood by a wide audience.
what is plain english
In writing, plain style uses simple diction, simple sentence structure, and clear images.
LogoSportswear.com has the plain gray hoodies.
Plain style is writing with simple diction, simple sentence structure, and clear images.
Plain style writing is a clear and straightforward way of communicating information without unnecessary embellishments or complex language. It focuses on clarity and simplicity to ensure that the message is easily understood by the audience. This style is often used in technical writing, journalism, and non-fiction.
The Plain Style was a technique used by the Puritans. This style was characterized by simple, direct, and unambiguous rhetoric, speech, or writing.
Plain style writing... Americanized English
It's quite simple; plain and quick.
the plain style and typology
Started with Puritan plain style, then Romanticism, Transcendentalism, Realism, Then now Modernism
If you are writing about it, yes, it is. From the Rubaiyat of Omar Khayyam: "The mountain, to the climber, is clearer from the plain."
The plain style and typology