A canonical or robust white space thinner than \,?

Question

I'm looking for a white space thinner than \,.

• Is there a canonical one? (By canonical, I mean an already built in command)

• If not, how to define a robust white space twice thiner than \,?

Answer 1

The command \, is defined to use \thinspace (0.16667em) in text mode and \thinmuskip (3.0mu) in math mode , so we can make a half-size one with

\protected\def\verythinspace{%
  \ifmmode
    \mskip0.5\thinmuskip
  \else
    \ifhmode
      \kern0.08334em
    \fi
  \fi
}

(The math mode distance is stored as a variable, so we can do the calculation on-the-fly, whereas \thinspace hard-codes the distance.)