On 2020-05-16 05:09, Mod wrote:
Unicode changed that by adding those as characters (code points), in
addition adding some styles that are not properly semantic, like sans
serif and monospace variations. (The sans serif style is used for
tensors by some engineers, but I have found no example in mathematics,
physics or computer science of that.)

[[Mod. note -- Checking a few general-relativity textbooks, I see that
Misner, Thorne, & Wheeler "Gravitation" (W.H. Freeman, 1973) uses sans
serif for tensors and differential forms, but none of the other books
I checked do this.
-- jt]]

They use bold sans-serif when not having indices, but switches to
non-bold serif, that is, plain italic, when having indices on the same
object. In mathematics, like in differential geometry, one uses serifs
and not switching styles, like between plain and bold, allowing the
styles to be used for more different types of objects objects.