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  "title" : "Model I/O Constants"
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# Model I/O Constants

## Topics

### Constants

[`let MDLVertexAttributeAnisotropy: String`](/documentation/ModelIO/MDLVertexAttributeAnisotropy)

The attribute data describes the degree to which a surface’s appearance changes in appearance when rotated about its normal vector.

[`let MDLVertexAttributeBinormal: String`](/documentation/ModelIO/MDLVertexAttributeBinormal)

The attribute data describes surface binormal vectors.

[`let MDLVertexAttributeBitangent: String`](/documentation/ModelIO/MDLVertexAttributeBitangent)

The attribute data describes surface bitangent vectors.

[`let MDLVertexAttributeColor: String`](/documentation/ModelIO/MDLVertexAttributeColor)

The attribute data describes vertex colors.

[`let MDLVertexAttributeEdgeCrease: String`](/documentation/ModelIO/MDLVertexAttributeEdgeCrease)

The attribute data describes edges that should be left unmodified by surface subdivision operations.

[`let MDLVertexAttributeJointIndices: String`](/documentation/ModelIO/MDLVertexAttributeJointIndices)

The attribute data describes the indices of bones or joints in a skeletal animation rig.

[`let MDLVertexAttributeJointWeights: String`](/documentation/ModelIO/MDLVertexAttributeJointWeights)

The attribute data describes the influence factors of bones or joints on a vertex’s position for use in skeletal animation.

[`let MDLVertexAttributeNormal: String`](/documentation/ModelIO/MDLVertexAttributeNormal)

The attribute data describes surface normal vectors.

[`let MDLVertexAttributeOcclusionValue: String`](/documentation/ModelIO/MDLVertexAttributeOcclusionValue)

The attribute data describes per-vertex ambient occlusion values.

[`let MDLVertexAttributePosition: String`](/documentation/ModelIO/MDLVertexAttributePosition)

The attribute data describes vertex positions.

[`let MDLVertexAttributeShadingBasisU: String`](/documentation/ModelIO/MDLVertexAttributeShadingBasisU)

The attribute data describes the U component of a vector basis for use in shading.

[`let MDLVertexAttributeShadingBasisV: String`](/documentation/ModelIO/MDLVertexAttributeShadingBasisV)

The attribute data describes the V component of a vector basis for use in shading.

[`let MDLVertexAttributeSubdivisionStencil: String`](/documentation/ModelIO/MDLVertexAttributeSubdivisionStencil)

The attribute data describes which neighboring vertices influence the effect of surface subdivision on the area around a vertex.

[`let MDLVertexAttributeTangent: String`](/documentation/ModelIO/MDLVertexAttributeTangent)

The attribute data describes surface tangent vectors.

[`let MDLVertexAttributeTextureCoordinate: String`](/documentation/ModelIO/MDLVertexAttributeTextureCoordinate)

The attribute data describes texture coordinates.

[`let kUTType3dObject: String`](/documentation/ModelIO/kUTType3dObject)

The Object file format (common extension `.obj`).

[`let kUTTypeAlembic: String`](/documentation/ModelIO/kUTTypeAlembic)

The Alembic file format (common extension `.abc`).

[`let kUTTypePolygon: String`](/documentation/ModelIO/kUTTypePolygon)

The Polygon file format (common extension `.ply`).

[`let kUTTypeStereolithography: String`](/documentation/ModelIO/kUTTypeStereolithography)

The Stereolithography file format (common extension `.stl`), also known as the Standard Tessellated Geometry format.

[`let kUTTypeUniversalSceneDescription: String`](/documentation/ModelIO/kUTTypeUniversalSceneDescription)

The Universal Scene Description file format (common extension `.usd`).

[`let kUTTypeUniversalSceneDescriptionMobile: String`](/documentation/ModelIO/kUTTypeUniversalSceneDescriptionMobile)


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