# Summary of 3GPP Technical Document S4-260166

## Document Information
- **Change Request**: CR 0002 rev 1 to TS 26.119 v18.0.0
- **Title**: Assignment of IVAS levels to device types
- **Source**: Dolby Laboratories Inc.
- **Work Items**: MeCAR, IVAS_Codec
- **Category**: F (correction)
- **Release**: Rel-18

## Purpose and Rationale

### Reason for Change
The specification previously lacked concrete assignments of IVAS (Immersive Voice and Audio Services) capabilities to XR device types. Placeholder notes indicated that such assignments would be made once IVAS capability levels were defined. Since IVAS capability levels are now specified, this CR removes the placeholder notes and provides the actual capability assignments.

### Consequences if Not Approved
Without this correction, implementers would remain unclear about which IVAS capability levels need to be implemented in AR/XR devices, leading to potential interoperability issues and implementation confusion.

## Technical Changes

The CR modifies four subclauses (10.2.4, 10.3.4, 10.4.4, and 10.5.4) corresponding to the four XR device types. The changes follow a consistent pattern across device types, with variations in the specific IVAS levels assigned.

### Device Type 1 (Clause 10.2.4)

**Decoding Capabilities:**
- **Should support**: Changed from generic "IVAS" with placeholder note to specific **"IVAS-SR"** capability
- Removed placeholder note about refinement

**Encoding Capabilities:**
- **Should support**: Changed from generic "IVAS" with placeholder note to specific **"IVAS-L1"** capability
- Removed placeholder note about refinement

### Device Type 2 (Clause 10.3.4)

**Decoding Capabilities:**
- **Should support**: Changed from generic "IVAS" with placeholder note to specific **"IVAS-L1"** capability
- Removed placeholder note about refinement

**Encoding Capabilities:**
- **Should support**: Changed from generic "IVAS" with placeholder note to specific **"IVAS-L1"** capability
- Removed placeholder note about refinement

### Device Type 3 (Clause 10.4.4)

**Decoding Capabilities:**
- **Should support**: Retains generic **"IVAS"** (full capability)
- Removed placeholder note about refinement

**Encoding Capabilities:**
- **Should support**: Retains generic **"IVAS"** (full capability)
- Removed placeholder note about refinement

### Device Type 4 (Clause 10.5.4)

**Decoding Capabilities:**
- **Should support**: Retains generic **"IVAS"** (full capability)
- Removed placeholder note about refinement

**Encoding Capabilities:**
- **Should support**: Retains generic **"IVAS"** (full capability)
- Removed placeholder note about refinement

## Implementation Approach

**Revision History:**
- **Initial version (SA4#134)**: Implemented changes with direct referencing of IVAS codec specifications
- **Rev 1 (SA4#135)**: Modified implementation to reference IVAS decoding capabilities in TS 26.117

## Related Specifications

This CR affects:
- **TS 26.117 CR 0013**: Related change request (presumably defining the IVAS capability levels referenced)

## Summary of IVAS Level Assignments

| Device Type | Decoding Capability | Encoding Capability |
|-------------|---------------------|---------------------|
| Type 1      | IVAS-SR            | IVAS-L1            |
| Type 2      | IVAS-L1            | IVAS-L1            |
| Type 3      | IVAS (full)        | IVAS (full)        |
| Type 4      | IVAS (full)        | IVAS (full)        |

The assignment shows a tiered approach where Device Types 1 and 2 support specific IVAS levels (SR and L1), while Device Types 3 and 4 support full IVAS capabilities, likely reflecting different device complexity and capability requirements.