Those are line-drawing and shading characters. They were used all the time in MS-DOS programs (to great good, in my opinion) for textual "windowing" UIs (a "TUI

Those are line-drawing and shading characters. They were used all the time in MS-DOS programs (to great good, in my opinion) for textual "windowing" UIs (a "TUI"). A good example is Turbo Vision: https://en.wikipedia.org/wiki/Turbo_Vision https://en.wikipedia.org/wiki/Turbo_Vision