<pedantic hat>
"." is commonly understood in this way, in plain text. It is a poor substitute, used when the correct symbol is unavailable.
While we can't [easily] change the image now, we can write it properly here: using LaTeX, \$ \cdot \$, using HTML ·, using Unicode, ยท.
The SI also accepts spaces (
https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-6-rules-and-style-conventions-printing-and-using 6.1.5), or, hmm, that's the NIST actually, but it's probably the same. Note that's a non-breaking space, of course.
</pedantic>

Tim