# YAML prefab serialization example > Annotated YAML excerpts of prefab instances, nested prefabs, and prefab variants from real files. This page demonstrates annotated YAML excerpts of prefab instances, nested prefabs, and prefab variants from Unity project files. The excerpts are trimmed for readability: the original files contain more `m_Modifications` entries than this page shows. For a description of the data model that these excerpts follow, refer to [YAML serialization of prefabs](/engine/6000.7/manual/working-with-scenes/text-scene-format/yaml-prefab-serialization.md). The page covers the following concepts: * [Prefab instance in a scene](#prefab-instance-in-a-scene) * [Nested prefab](#nested-prefab) * [Prefab variant](#prefab-variant) ## Prefab instance in a scene ##prefab-instance-in-a-scene The following excerpt is from a scene file that places an instance of a rock prefab into the scene. The instance overrides the rock's position, rotation, and name. ```lang-yml --- !u!1001 &11866470 PrefabInstance: m_ObjectHideFlags: 0 serializedVersion: 2 m_Modification: serializedVersion: 3 m_TransformParent: {fileID: 1122852772} m_Modifications: - target: {fileID: 599465214307944399, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} propertyPath: m_LocalPosition.x value: 39.341 objectReference: {fileID: 0} - target: {fileID: 599465214307944399, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} propertyPath: m_LocalPosition.y value: 4.425 objectReference: {fileID: 0} - target: {fileID: 599465214307944399, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} propertyPath: m_LocalPosition.z value: 26.527 objectReference: {fileID: 0} - target: {fileID: 599465214307944399, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} propertyPath: m_LocalRotation.w value: 0.69781095 objectReference: {fileID: 0} - target: {fileID: 8354524949365800270, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} propertyPath: m_Name value: Rock_05_Prefab (4) objectReference: {fileID: 0} m_RemovedComponents: [] m_RemovedGameObjects: [] m_AddedGameObjects: [] m_AddedComponents: [] m_SourcePrefab: {fileID: 100100000, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} --- !u!4 &11866471 stripped Transform: m_CorrespondingSourceObject: {fileID: 599465214307944399, guid: 95cf80858ee0c4940b72f62b17aefd41, type: 3} m_PrefabInstance: {fileID: 11866470} m_PrefabAsset: {fileID: 0} ``` Key points in the excerpt: * The `PrefabInstance` element with fileID `11866470` represents the instance. Its `m_SourcePrefab` field references the rock prefab asset (by `guid`) through the prefab asset handle (fileID `100100000`). * `m_Modification.m_TransformParent` references a `Transform` component in the same scene file, making the prefab instance a child of that scene object in the hierarchy. * Each entry in `m_Modifications` contains one property override. The `target` identifies the object inside the source prefab by `guid` and `fileID`, and a combination of `propertyPath` and `value` specify the overridden property and its value. * The stripped `Transform` element (element with the `stripped` attribute) at fileID `11866471` is a placeholder for the `Transform` component on the prefab instance's root GameObject. Other objects in the scene use this placeholder whenever they reference the prefab instance's root, for example in the `m_Children` list of the parent scene object's `Transform` component. The original `m_Modifications` list in the source file also contains the other rotation components and euler-angle-hint overrides; they're omitted here for readability. ## Nested prefab ##nested-prefab The following example is the complete prefab file that nests one other prefab inside it. ```lang-yml %YAML 1.1 %TAG !u! tag:unity3d.com,2011: --- !u!1 &6949479575104989305 GameObject: m_ObjectHideFlags: 0 m_CorrespondingSourceObject: {fileID: 0} m_PrefabInstance: {fileID: 0} m_PrefabAsset: {fileID: 0} serializedVersion: 6 m_Component: - component: {fileID: 1188189139150009913} m_Layer: 0 m_Name: Stone_01_Prefab m_TagString: Untagged m_Icon: {fileID: 0} m_NavMeshLayer: 0 m_StaticEditorFlags: 2147483647 m_IsActive: 1 --- !u!4 &1188189139150009913 Transform: m_ObjectHideFlags: 0 m_CorrespondingSourceObject: {fileID: 0} m_PrefabInstance: {fileID: 0} m_PrefabAsset: {fileID: 0} m_GameObject: {fileID: 6949479575104989305} m_LocalRotation: {x: 0, y: 0, z: 0, w: 1} m_LocalPosition: {x: 0, y: 0, z: 0} m_LocalScale: {x: 1, y: 1, z: 1} m_ConstrainProportionsScale: 0 m_Children: - {fileID: 8712595929885449456} m_Father: {fileID: 0} m_RootOrder: 0 m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0} --- !u!1001 &9179429690634107675 PrefabInstance: m_ObjectHideFlags: 0 serializedVersion: 2 m_Modification: serializedVersion: 3 m_TransformParent: {fileID: 1188189139150009913} m_Modifications: - target: {fileID: 919132149155446097, guid: 5a62bd76f7db850498f128cc2e7b59d2, type: 3} propertyPath: m_Name value: Stone_01_Mesh objectReference: {fileID: 0} - target: {fileID: 4742473837712756890, guid: 5a62bd76f7db850498f128cc2e7b59d2, type: 3} propertyPath: m_FadeMode value: 1 objectReference: {fileID: 0} - target: {fileID: 4742473837712756890, guid: 5a62bd76f7db850498f128cc2e7b59d2, type: 3} propertyPath: m_AnimateCrossFading value: 1 objectReference: {fileID: 0} m_RemovedComponents: [] m_RemovedGameObjects: - {fileID: -1027982724379016789, guid: 5a62bd76f7db850498f128cc2e7b59d2, type: 3} m_AddedGameObjects: [] m_AddedComponents: [] m_SourcePrefab: {fileID: 100100000, guid: 5a62bd76f7db850498f128cc2e7b59d2, type: 3} --- !u!4 &8712595929885449456 stripped Transform: m_CorrespondingSourceObject: {fileID: -8679921383154817045, guid: 5a62bd76f7db850498f128cc2e7b59d2, type: 3} m_PrefabInstance: {fileID: 9179429690634107675} m_PrefabAsset: {fileID: 0} ``` Key points in the example: * The outer prefab's root is serialized as two separate YAML elements: a `GameObject` element (fileID `6949479575104989305`) and its `Transform` component element (fileID `1188189139150009913`). Unity writes them both directly into the file, the same way it writes any non-prefab GameObject. * The `m_Children` field on the outer `Transform` component element lists the fileID of the stripped `Transform` placeholder element for the nested instance (`8712595929885449456`). This reference places the nested prefab's root as a child in the outer prefab's hierarchy. * The `PrefabInstance` element with fileID `9179429690634107675` represents the nested prefab instance. Its `m_SourcePrefab` field references a different prefab asset (the `Stone` source prefab), identified by `guid`. * The `m_Modification.m_TransformParent` field on the nested `PrefabInstance` references the outer `Transform` component element. As a result, the nested instance is placed under the outer prefab's root in the hierarchy. * The stripped `Transform` placeholder element at fileID `8712595929885449456` is the target that the outer `Transform` component's `m_Children` field points to. Its `m_CorrespondingSourceObject` field identifies the specific `Transform` component inside the source `Stone` prefab that this placeholder represents. * The `m_RemovedGameObjects` list contains one entry, which indicates that one child GameObject from the source prefab is removed from this nested instance. The `m_RemovedComponents` and `m_AddedGameObjects` lists are empty. The original `m_Modifications` list in the source file contains additional transform and static flag overrides, they're omitted here for readability. ## Prefab variant ##prefab-variant The following excerpt is from a prefab variant file. The variant is a horizontally flipped version of a base door prefab. ```lang-yml %YAML 1.1 %TAG !u! tag:unity3d.com,2011: --- !u!1001 &5365984487090290000 PrefabInstance: m_ObjectHideFlags: 0 serializedVersion: 2 m_Modification: serializedVersion: 3 m_TransformParent: {fileID: 0} m_Modifications: - target: {fileID: 1262770979034925880, guid: 89d4c08db6b9096438cb6c7718d47f26, type: 3} propertyPath: m_Name value: DoorFusuma_100x200_01_Prefab (38) Variant objectReference: {fileID: 0} - target: {fileID: 1727893522013754926, guid: 89d4c08db6b9096438cb6c7718d47f26, type: 3} propertyPath: m_LocalScale.x value: -1 objectReference: {fileID: 0} - target: {fileID: 1761800793405478535, guid: 89d4c08db6b9096438cb6c7718d47f26, type: 3} propertyPath: m_LocalScale.x value: -1 objectReference: {fileID: 0} - target: {fileID: 7660580366407964633, guid: 89d4c08db6b9096438cb6c7718d47f26, type: 3} propertyPath: m_LocalScale.x value: -1 objectReference: {fileID: 0} m_RemovedComponents: [] m_RemovedGameObjects: [] m_AddedGameObjects: [] m_AddedComponents: [] m_SourcePrefab: {fileID: 100100000, guid: 89d4c08db6b9096438cb6c7718d47f26, type: 3} ``` Key points in the excerpt: * The root YAML element of the variant file is a `PrefabInstance`, which has class ID `1001`. A non-variant prefab file, by contrast, starts with a `GameObject` element. * The `m_Modification.m_TransformParent` field is `{fileID: 0}`. The `PrefabInstance` element has no parent transform because it's the root of the file. This is characteristic of prefab variants. * The `m_SourcePrefab` field references the base prefab that the variant inherits from. * The entries in the `m_Modifications` list contain the property overrides that make this variant distinct from the base. In this example, the negative `m_LocalScale.x` property values on three `Transform` components flip the door geometry horizontally. The original file contains additional transform and position overrides that complete the flipped layout, they're omitted here for readability. ## Additional resources * [YAML serialization of prefabs](/engine/6000.7/manual/working-with-scenes/text-scene-format/yaml-prefab-serialization.md) * [Format of text serialized files](/engine/6000.7/manual/working-with-scenes/text-scene-format/format-description.md) * [An example of a YAML scene file](/engine/6000.7/manual/working-with-scenes/text-scene-format/yamlscene-example.md) * [YAML class ID reference](/engine/6000.7/manual/working-with-scenes/text-scene-format/class-idreference.md) * [Nest prefab instances in other prefabs](/engine/6000.7/manual/working-with-gameobjects/prefabs/nested.md) * [Create variations of prefabs](/engine/6000.7/manual/working-with-gameobjects/prefabs/prefab-variants.md) * [Smart merge](/engine/6000.7/manual/get-started/project-configuration/version-control/smart-merge.md)