R>DROP R> R@
R>DROP ( -- )  
<PFE-MISC>
shortcut (e.g. in CSI-Forth)
note that
 : R>DROP R> DROP ; 
would be wrong - for a non-direct-threaded forth it would be
 : R>DROP R> R> NIP >R ;

reference: p4_r_from_drop in ../src/misc.c:0265, export CO R>DROP