i;ascii-numeric comparator issue

   I am trying to implement the i;ascii-numeric comparator and 
according to rfc 2244 : "All values which do not begin with a US-ASCII 
digit are considered equal with an ordinal value higher than all non-NIL 
single-valued"
  I understand for this that if I have a value that begins with other 
that a digit, i give it the highest value in my interval (for ex. 2^32 
given an interval of 0 - 2^32-1). But what happens if I compare 2 values 
starting with a non-digit character? Are they  equal? What if I have  a 
""  string (a  NULL  value)?
 If i make the assumtion that all values starting with a non-digit or 
NULL value are equal to 2^32, then the following code will behave wrong
if address :is :all :i;ascii-numeric "To" "aa" {
   discard;
}
if address :is :all :i;ascii-numeric "From" "" {
   discard;
}
both tests will evaluate to true which, for the seccond case, explicitly 
contradicts the base RFC (3028)
any ideas?