[]               Index Operator                                 MASM Operator

  expression1[expression2]

    Adds the value of expression1 to the value of expression2.  This
    operator is the same as the plus-operator ('+'), except expression1 is
    optional for this operator.

       Notes:     If expression1 is specified, it can be an integer value,
                  relocatable operand, or absolute symbol.  Expression2
                  can be an integer value, relocatable operand, or
                  absolute symbol, unless expression1 is specified, in
                  which case expression2 can not be a relocatable operand.

                  This operator is generally used to access individual
                  items in an array.  For example, the following will
                  access the third byte of a character string.

                       MOV       AL, STRING [2]