[ibdknox]

You could do even better than this if you wanted. Since there are only between 100-200 dom attributes, you can pack that into the opcode itself. Assuming 6 bits for the opcode (64 ops) and 8 bits for the dom attribute (256 attrs), you still have another 18bits to play with in a 32 bit int. If you wanted to allow arbitrary attributes, you could dictionary encode them and then use the full 26 bits for a total of 67M possible attribute names. Alternatively, you can reduce that entire op down to just the opcode by dictionary encoding the operand and packing that in as well. How many programs have more than 262,000 static strings? :)

Compared to the string encoding above we went from 14 chars (1-4 bytes each, we'll just say 2) at 28 bytes to 4 bytes for our 32 bit int.