Section: C.3.4 Guidelines for the allocation of the index values in the array scheme
Content: - General rule: index values used in the array scheme, according to Annex C.1.2, shall be allocated cyclically within its range 0, ... , a-1. This means that the index value used with the previously generated authentication vector is stored in SQNHE , and the next authentication vector shall use index value +1 mod a. It may be useful to allow exceptions to this general rule when additional information is available. This includes: - Authentication vectors distributed within the same batch shall have the same index value. The Authentication Data Request MAP message contains information about the domain type (CS or PS) of the requesting serving node from which the request originates. It is recommended to use this information in the following way. Support for this use is, however, not required for an implementation to claim compliance to Annex C. - Authentication vectors distributed to different service domains shall have different index values (i.e. separate ranges of index values are reserved for PS and CS operation). In future releases there may be additional information about the requesting node identity. If this information is available it is recommended to use it in the following way: - If the new request comes from the same serving node as the previous request, then the index value used for the new request shall be the same as was used for the previous request.