Concatenative Hardware Redux (Another 16 Instruction Set)

Hi all,

Here is my most recent 16 instruction set for concatenative hardware.
Any comments would be greatly appreciated.

/*
 * Released into the public domain by Christopher Diggins
 * Contact me if you have special licensing requirements
 * http://www.cdiggins.com
 */

enum
{
        /* Push a literal value from the instruction stream */
        LIT = 0, /* -> a */

        /* Add top two values on the stack */
        ADD = 1, /* a b -> (a + b) */

        /* Shift second value on the stack left or right */
        SHIFT = 2, /* a b -> b < 32 ? (a >> b) : (a << (b - 32)) */

        /* Perform exclusive or of top two values */
        XOR = 3, /* a b -> (a ^ b) */

        /* Perfrom bitwise and of top two values */
        AND = 4, /* a b -> (a & b) */

        /* Dynamic function/list construction */
        /* Note: lists and functions are identical from a programmer's perspective,
                a list is the result of a function that consumes nothing. Think of it
                as a new stack yielded by executing the function, except that it is
                lazy (evaluated at last minute) */
        PAPPLY = 5,  /* a [X] -> [a X] */
        COMPOSE = 6,  /* [X] [Y] -> [X Y] */

        /* Branching and calling */
        APPLYIF = 7,  /* bool [X] -> X or NOOP */
       
        /* Reference creation and manipulation, used for playing with heap */
        MAKEREF = 8,  /* a -> &a */
        GETREF = 9,  /* &a -> a */
        SETREF = 10, /* &a b -> &(*a = b) */

        /* Stack manipulation operations */
        FLIP = 11, /* a X b n:int -> b X a ; sizeof(X) == n */
        GETN = 12, /* a X n:int -> (a X, a) ; sizeof(X) == n */
        SETN = 13, /* (a X n:int, b) -> b X ; sizeof(X) == n */

        /* Applies a function to a list */
        APPPLYTO = 14, /* [->X] [X->Y] => [Y] */

                /* Make a suggestion ( I was thinking of COUNT, but I
am not so sure ) */
                UNUSED = 15
}
opcodes;

/*
Some examples of derived opcodes:

        SWAP = 0 FLIPN
        DUP = 0 GETN
        POPD = 0 SETN
        POP = SWAP POPD
        QUOTE = [] CONS
        APPLY = TRUE SWAP APPLYIF
        CONS = SWAP QUOTE PAPPLY
        UNCONS = APPLY SWAP
        DIP = SWAP QUOTE COMPOSE APPLY
*/

Christopher Diggins
http://www.cat-language.com