# 3GPP TR 26.502 Change Request - MBSF Notification Event Corrections

## General Information

- **CR Number:** 0048
- **Release:** Rel-19
- **Category:** A (mirror corresponding to a change in an earlier release)
- **Work Item:** 5MBUSA (5G MBS User Service Architecture)
- **Source:** BBC
- **Meeting:** S4#135, Goa, India, 9th-13th February 2026

## 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 level in TR 26.502. This issue is tracked in the 5G-MAG GitHub repository (issue #11).

2. **Errors in notification event depiction:** Figure 5.3-2 contains errors in the depiction of event notifications (tracked in 5G-MAG GitHub issue #188).

Without approval, there would be misalignment between SA4 (stage-2) and CT3 (stage-3) normative specifications, and the MBSF could not be implemented as currently specified.

## Technical Changes

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

**Modifications to Table 4.6.2-1:**

- **Column simplification:** The final column has been renamed from "Applicable reference point(s)" to "Stimulating reference point(s)" for improved clarity
- **Added motivation for two missing events:**
  - **Distribution Session service management failure:** Added stimulating reference points (Nmb1), (Nmb2), Nmb10/Nmb5
  - **Distribution Session policy control failure:** Added stimulating reference points (Nmb12), Nmb10/Nmb5

The table now properly indicates which reference points stimulate each notification event, with brackets indicating when the event originates from another NF and is propagated through the MBSF.

### Change 2: Clause 5.3 - User Service Provisioning Procedures

**Corrections to Figure 5.3-2 call flow steps:**

- **Step 14:** Corrected to specify that MBSTF invokes `Nmbstf_MBSDistributionSession_StatusNotify` (not the previous incorrect reference)
  
- **Step 15:** Corrected to specify that MBSF invokes `Nmbsf_MBSUserDataIngestSession_StatusNotify` to inform the MBS Application Provider about establishment success/failure of content ingest for the MBS Distribution Session

- **Step 17:** Corrected to specify that MBSF invokes `Nmbsf_MBSUserDataIngestSession_StatusNotify` to inform about the establishment status of **all** MBS Distribution Sessions of the parent MBS User Data Ingest Session (not just individual sessions)

## Impact

- **TS 26.502:** This CR aligns the specification with TS 29.580
- **TS 29.580:** No impact on the CT3 specification
- **Other specifications:** No impact on other core, test, or O&M specifications