I'm familiar with some of the different conventions used in different parts of the world to separate integer parts from fractional parts: a dot ($.$) in the English-speaking world, a comma ($,$) in continental Europe, a different kind of comma-like character (whose Unicode ID and TeX code I don't know) in the Arab world.
I'm also aware the decimal point was typically written in the middle of the line (as opposed to the bottom) in older English-language texts (as recently as the middle of the 20th century).
However, the other day I came across the notation $\stackrel{\text{m}}{\cdot}$ in an astrophysics article. This one is new to me. Is the m supposed to represent something specific? (I'm not an astrophysicist, so I wouldn't know.) From context, it seems to be equivalent to the regular decimal point.
(The article also seems to use the (incredibly weird to me) notation $\lambda5000$ to denote a wavelength of 5,000 (given they are referring to the reflectivity of Uranus, which has a maximum close to 500 nm, It's clear $\lambda5000$ means 5,000 Å, which is no more difficult to write than $\lambda5000$ and is rather confusing to (at least some) scientists from other areas). Maybe the m, like this wavelength notation, is just a weird astrophysicist quirk...)