The length (i.e. number of octets) of the source ID of
a KEK Policy/SA. If no length is given (i.e. it has a value
of 0), the default length of its cgmGdoiKsKekSrcIdType 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 'SRC ID Data Len' field sent in the KEK
payload.