The architecture for the control and the interrogation of subscription data described in the
clause 10 in TS 23.078 Rel-99 for the HLR and the gsmSCF also applies for the HSS and the gsmSCF.
This clause contains the detailed description of the information flows used by CAMEL for control and interrogation of subscription data.
Each Information Element (IE) is marked as Mandatory (M), Conditional (C), Specific conditions (S), mutually Exclusive (E) or Optional (O).
An 'M' IE shall always be included. A 'C' IE shall be included if the sending entity has the necessary information to populate the IE. The conditions for the inclusion of an 'S' IE are shown in the 'Description' column of the definition table. An 'O' IE may be included or omitted as required by the service logic. This categorization is a functional classification, i.e. it defines the requirements for the stage 2 information. It is not a stage 3 classification to be used for the ASN.1 syntax of the protocol.
The following principles apply for the handling of the IEs by the receiving entity:
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The gsmSCF may silently discard any IE which it does not functionally support.
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The HSS shall return an error if it does not functionally support an IE which it receives.
Details of errors and exceptions to these rules are specified in
TS 29.002.