4DUP 3DUP :
4DUP ( a b c d -- a b c d a b c d )  
<FORTH-83-L&P>
 simulate:
  : 4DUP  4 PICK 4 PICK 4 PICK 4 PICK ;

reference: p4_four_dup in ../src/lpf83.c:0183, export CO 4DUP