Rasagar/Library/PackageCache/com.unity.render-pipelines.high-definition/Documentation~/snippets/shader-properties/emission-inputs/emission-uv-mapping-layered-tessellation.md

Emissive Color Specifies the type of UV mapping to uses for the Emission Map.
• Unity manages four UV channels for a vertex: UV0, UV1, UV2, and UV3.
• Planar: A planar projection from top to bottom.
• Triplanar: A planar projection in three directions:
• X-axis: Left to right
• Y-axis: Top to bottom
• Z-axis: Front to back

Unity blends these three projections together to produce the final result.
• Same as Main Layer: Unity uses the option selected for Main Layer > Surface Inputs > Base UV Mapping.