if(foo == TRUE) .. etc

Great suggestion; it made me change all my Ts/Fs to TRUE/FALSE.
Given
  F <- TRUE
  T <- FALSE
is it possible to forbid T to stand for TRUE, and F for FALSE in
  function(...,something=T)?
Or, alternatively, never allow F <- whatever and T <- whatever?

Allowing T and F to be used as variables is deliberate. R CMD check will 
check to see if you use T and F without defining them, which catches most 
examples.  This is done using makeActiveBinding, see the help to find out 
how you can use it yourself.

 	-thomas