ansi .6.1.0580
<CORE>
save the value onto the return stack. The return
stack must be returned back to clean state before
an exit and you should note that the return-stack
is also touched by the DO ... WHILE loop.
Use R> to clean the stack and R@ to get the
last value put by >R
reference: p4_to_r in ../src/core.c:0610, export CO >R