[R] Change font-face in title

[Mike Prager]

"Gabor Grothendieck" <ggrothendieck at gmail.com> wrote:
> 
> plot(1, type="l", xlab="Wellenlänge [nm]", col="darkslategray",
>       main = ~ Spektrum ~ italic("Deschampsia caespitosa"))
 
That clearly works, but why?  Does the tilde cause the rest of
the text to be parsed as an expression?  This looks extremely
useful, and I am grasping for the underlying principle.

-- 
Mike Prager, NOAA, Beaufort, NC
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