# Change Request Summary: 26.502 CR 0046 Rev 1

## Document Information
- **CR Number**: 0046 Rev 1
- **Release**: Rel-17
- **Category**: F (Correction)
- **Work Item**: 5MBUSA
- **Title**: [5MBUSA] MBSF notification event corrections

## Reason for Change

This CR addresses two main issues:

1. **Misalignment between Stage-2 and Stage-3 specifications**: Two notification events specified by CT3 in TS 29.580 are not properly motivated at stage-2 in TS 26.502
   - Reference: https://github.com/5G-MAG/rt-mbs-function/issues/11

2. **Errors in notification event depiction**: Figure 5.3-2 contains errors in the depiction of event notifications
   - Reference: https://github.com/5G-MAG/Standards/issues/188

## Technical Changes

### Change 1: Clause 4.6.2 - Notification Events Table

**Modifications to Table 4.6.2-1**:

- **Column simplification**: The final column "Applicable reference point(s)" has been renamed to "Stimulating reference point(s)" for improved clarity
- **Clarification of event origins**: The text now better explains that events in brackets originate from other NFs, while events without brackets originate from the MBSF itself

**Addition of two missing notification events**:

1. **Distribution Session service management failure**
   - Description: The MBS Distribution Session could not be started because necessary resources could not be allocated by the MBS System
   - Stimulating reference points: (Nmb1), (Nmb2), Nmb10/Nmb5

2. **Distribution Session policy control failure**
   - Description: The MBS Distribution Session could not be started because of a policy authorization/control failure or rejection
   - Stimulating reference points: (Nmb12), Nmb10/Nmb5

### Change 2: Clause 5.3 - Procedure Corrections in Figure 5.3-2

**Step 14 correction**:
- Changed service operation from generic notification to **`Nmbstf_MBSDistributionSession_StatusNotify`** callback service operation
- Clarified that this informs the MBSF of (un)successful establishment of content ingest using the **Distribution Session established** event
- Added state transition information: On success → `ESTABLISHED`, on failure → remains `INACTIVE`

**Step 15 correction**:
- Changed service operation to **`Nmbsf_MBSUserDataIngestSession_StatusNotify`** callback service operation
- Clarified that this informs the MBS Application Provider of (un)successful establishment of content ingest
- Specified use of either **Distribution Session established** event or **Distribution Session establishment failure** event, as appropriate

**Step 17 correction**:
- Changed service operation to **`Nmbsf_MBSUserDataIngestSession_StatusNotify`** callback service operation
- Clarified that this informs the MBS Application Provider of (un)successful establishment of **all** MBS Distribution Sessions
- Specified use of either **User Data Ingest Session established** event or **User data ingest failure** event, as appropriate

## Impact

- **Alignment achieved**: TS 26.502 (SA4) now properly aligns with TS 29.580 (CT3)
- **Implementation clarity**: The MBSF can now be implemented correctly according to the specification
- **No impact on TS 29.580**: Changes are confined to TS 26.502