The length (i.e. number of octets) of the destination ID of
a KEK Policy/SA (multicast rekey address). If no length is
given (i.e. it has a valueof 0), the default length of its
cgmGdoiKsKekDstIdType should be used as long as it is not
reprsented by an ASCII string. If the value has a type that
is represented by an ASCII string, a length MUST be included.
If the length given is not 0, it should match the 'DST ID Data
Len' field sent in the KEK payload.