Section: 1.2 Application to the interface structures
Content: The procedures defined in the present document apply to the interface structures defined in 3GPP TS 44.003[ None ]  [16] and 3GPP TS 25.301[ None ]  [128]. They use the functions and services provided by lower layers defined in 3GPP TS 44.005[ None ]  [18] and 3GPP TS 44.006[ None ]  [19] or 3GPP TS 25.331[ None ]  [23c], 3GPP TS 25.322[ None ]  [19b] and 3GPP TS 25.321[ None ]  [19a]. 3GPP TS 24.007[ Mobile radio interface signalling layer 3; General Aspects ]  [20] gives the general description of layer 3 (A/Gb mode) and Non Access Stratum (Iu mode and S1 mode) including procedures, messages format and error handling.