backticks

I noticed just now that
package.skeleton() produces R files in which
the function names are escaped with backticks.

?Quotes says that "The preferred quote is the backtick (`)",
but I don't understand _why_  this is preferred.

?formula gives some clues but points out that there
are no guarantees that formulae using non-syntactic names such as
`like this` will be accepted.

What exactly do backticks do that single or double quotes don't?
Where do I look for documentation on this?




--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743