user: Give a detailed overview of Custom Properties: syntax, arguments, return values, common patterns.

assistant: PropertyGroups are the base class for dynamically defined sets of properties.

They can be used to extend existing Blender data with your own types which can
be animated, accessed from the user interface and from Python.

```
import bpy

class MyPropertyGroup(bpy.types.PropertyGroup):
    custom_1: bpy.props.FloatProperty(name="My Float")
    custom_2: bpy.props.IntProperty(name="My Int")

bpy.utils.register_class(MyPropertyGroup)

bpy.types.Object.my_prop_grp = bpy.props.PointerProperty(type=MyPropertyGroup)

# Test this worked.
bpy.data.objects[0].my_prop_grp.custom_1 = 22.0
```

base class — [`bpy_struct`](bpy.types.bpy_struct.html#bpy.types.bpy_struct "bpy.types.bpy_struct")

subclasses —
[`OperatorFileListElement`](bpy.types.OperatorFileListElement.html#bpy.types.OperatorFileListElement "bpy.types.OperatorFileListElement"), [`OperatorMousePath`](bpy.types.OperatorMousePath.html#bpy.types.OperatorMousePath "bpy.types.OperatorMousePath"), [`OperatorStrokeElement`](bpy.types.OperatorStrokeElement.html#bpy.types.OperatorStrokeElement "bpy.types.OperatorStrokeElement"), [`SelectedUvElement`](bpy.types.SelectedUvElement.html#bpy.types.SelectedUvElement "bpy.types.SelectedUvElement")

*class* bpy.types.PropertyGroup(*bpy_struct*)
:   Group of ID properties

    name
    :   Unique name used in the code and scripting

        Type:
        :   string, default “”, (never None)

    bl_system_properties_get(*\**, *do_create=False*)
    :   DEBUG ONLY. Internal access to runtime-defined RNA data storage, intended solely for testing and debugging purposes. Do not access it in regular scripting work, and in particular, do not assume that it contains writable data

        Parameters:
        :   **do_create** (*boolean**,* *(**optional**)*) – Ensure that system properties are created if they do not exist yet

        Returns:
        :   The system properties root container, or None if there are no system properties stored in this data yet, and its creation was not requested

        Return type:
        :   [`PropertyGroup`](#bpy.types.PropertyGroup "bpy.types.PropertyGroup")

    *classmethod* bl_rna_get_subclass(*id*, *default=None*, */*)
    :   Parameters:
        :   **id** (*str*) – The RNA type identifier.

        Returns:
        :   The RNA type or default when not found.

        Return type:
        :   [`bpy.types.Struct`](bpy.types.Struct.html#bpy.types.Struct "bpy.types.Struct") subclass

    *classmethod* bl_rna_get_subclass_py(*id*, *default=None*, */*)
    :   Parameters:
        :   **id** (*str*) – The RNA type identifier.

        Returns:
        :   The class or default when not found.

        Return type:
        :   type

### Inherited Properties

|  |  |
| --- | --- |
| - [`bpy_struct.id_data`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.id_data "bpy.types.bpy_struct.id_data") |  |

### Inherited Functions

|  |  |
| --- | --- |
| - [`bpy_struct.as_pointer`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.as_pointer "bpy.types.bpy_struct.as_pointer") - [`bpy_struct.driver_add`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.driver_add "bpy.types.bpy_struct.driver_add") - [`bpy_struct.driver_remove`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.driver_remove "bpy.types.bpy_struct.driver_remove") - [`bpy_struct.get`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.get "bpy.types.bpy_struct.get") - [`bpy_struct.id_properties_clear`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.id_properties_clear "bpy.types.bpy_struct.id_properties_clear") - [`bpy_struct.id_properties_ensure`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.id_properties_ensure "bpy.types.bpy_struct.id_properties_ensure") - [`bpy_struct.id_properties_ui`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.id_properties_ui "bpy.types.bpy_struct.id_properties_ui") - [`bpy_struct.is_property_hidden`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.is_property_hidden "bpy.types.bpy_struct.is_property_hidden") - [`bpy_struct.is_property_overridable_library`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.is_property_overridable_library "bpy.types.bpy_struct.is_property_overridable_library") - [`bpy_struct.is_property_readonly`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.is_property_readonly "bpy.types.bpy_struct.is_property_readonly") - [`bpy_struct.is_property_set`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.is_property_set "bpy.types.bpy_struct.is_property_set") - [`bpy_struct.items`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.items "bpy.types.bpy_struct.items") | - [`bpy_struct.keyframe_delete`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.keyframe_delete "bpy.types.bpy_struct.keyframe_delete") - [`bpy_struct.keyframe_insert`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.keyframe_insert "bpy.types.bpy_struct.keyframe_insert") - [`bpy_struct.keys`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.keys "bpy.types.bpy_struct.keys") - [`bpy_struct.path_from_id`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.path_from_id "bpy.types.bpy_struct.path_from_id") - [`bpy_struct.path_from_module`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.path_from_module "bpy.types.bpy_struct.path_from_module") - [`bpy_struct.path_resolve`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.path_resolve "bpy.types.bpy_struct.path_resolve") - [`bpy_struct.pop`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.pop "bpy.types.bpy_struct.pop") - [`bpy_struct.property_overridable_library_set`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.property_overridable_library_set "bpy.types.bpy_struct.property_overridable_library_set") - [`bpy_struct.property_unset`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.property_unset "bpy.types.bpy_struct.property_unset") - [`bpy_struct.rna_ancestors`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.rna_ancestors "bpy.types.bpy_struct.rna_ancestors") - [`bpy_struct.type_recast`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.type_recast "bpy.types.bpy_struct.type_recast") - [`bpy_struct.values`](bpy.types.bpy_struct.html#bpy.types.bpy_struct.values "bpy.types.bpy_struct.values") |

### References

|  |  |
| --- | --- |
| - [`AddonPreferences.bl_system_properties_get`](bpy.types.AddonPreferences.html#bpy.types.AddonPreferences.bl_system_properties_get "bpy.types.AddonPreferences.bl_system_properties_get") - [`Bone.bl_system_properties_get`](bpy.types.Bone.html#bpy.types.Bone.bl_system_properties_get "bpy.types.Bone.bl_system_properties_get") - [`BoneCollection.bl_system_properties_get`](bpy.types.BoneCollection.html#bpy.types.BoneCollection.bl_system_properties_get "bpy.types.BoneCollection.bl_system_properties_get") - [`CollectionExport.export_properties`](bpy.types.CollectionExport.html#bpy.types.CollectionExport.export_properties "bpy.types.CollectionExport.export_properties") - [`EditBone.bl_system_properties_get`](bpy.types.EditBone.html#bpy.types.EditBone.bl_system_properties_get "bpy.types.EditBone.bl_system_properties_get") - [`GizmoGroupProperties.bl_system_properties_get`](bpy.types.GizmoGroupProperties.html#bpy.types.GizmoGroupProperties.bl_system_properties_get "bpy.types.GizmoGroupProperties.bl_system_properties_get") - [`GizmoProperties.bl_system_properties_get`](bpy.types.GizmoProperties.html#bpy.types.GizmoProperties.bl_system_properties_get "bpy.types.GizmoProperties.bl_system_properties_get") - [`ID.bl_system_properties_get`](bpy.types.ID.html#bpy.types.ID.bl_system_properties_get "bpy.types.ID.bl_system_properties_get") - [`IDPropertyWrapPtr.bl_system_properties_get`](bpy.types.IDPropertyWrapPtr.html#bpy.types.IDPropertyWrapPtr.bl_system_properties_get "bpy.types.IDPropertyWrapPtr.bl_system_properties_get") - [`KeyConfigPreferences.bl_system_properties_get`](bpy.types.KeyConfigPreferences.html#bpy.types.KeyConfigPreferences.bl_system_properties_get "bpy.types.KeyConfigPreferences.bl_system_properties_get") - [`Node.bl_system_properties_get`](bpy.types.Node.html#bpy.types.Node.bl_system_properties_get "bpy.types.Node.bl_system_properties_get") - [`NodeSocket.bl_system_properties_get`](bpy.types.NodeSocket.html#bpy.types.NodeSocket.bl_system_properties_get "bpy.types.NodeSocket.bl_system_properties_get") - [`NodeTreeInterfaceSocket.bl_system_properties_get`](bpy.types.NodeTreeInterfaceSocket.html#bpy.types.NodeTreeInterfaceSocket.bl_system_properties_get "bpy.types.NodeTreeInterfaceSocket.bl_system_properties_get") | - [`NodesModifier.bl_system_properties_get`](bpy.types.NodesModifier.html#bpy.types.NodesModifier.bl_system_properties_get "bpy.types.NodesModifier.bl_system_properties_get") - [`OperatorProperties.bl_system_properties_get`](bpy.types.OperatorProperties.html#bpy.types.OperatorProperties.bl_system_properties_get "bpy.types.OperatorProperties.bl_system_properties_get") - [`PoseBone.bl_system_properties_get`](bpy.types.PoseBone.html#bpy.types.PoseBone.bl_system_properties_get "bpy.types.PoseBone.bl_system_properties_get") - [`PropertyGroup.bl_system_properties_get`](#bpy.types.PropertyGroup.bl_system_properties_get "bpy.types.PropertyGroup.bl_system_properties_get") - [`PropertyGroupItem.collection`](bpy.types.PropertyGroupItem.html#bpy.types.PropertyGroupItem.collection "bpy.types.PropertyGroupItem.collection") - [`PropertyGroupItem.group`](bpy.types.PropertyGroupItem.html#bpy.types.PropertyGroupItem.group "bpy.types.PropertyGroupItem.group") - [`PropertyGroupItem.idp_array`](bpy.types.PropertyGroupItem.html#bpy.types.PropertyGroupItem.idp_array "bpy.types.PropertyGroupItem.idp_array") - [`Strip.bl_system_properties_get`](bpy.types.Strip.html#bpy.types.Strip.bl_system_properties_get "bpy.types.Strip.bl_system_properties_get") - [`TimelineMarker.bl_system_properties_get`](bpy.types.TimelineMarker.html#bpy.types.TimelineMarker.bl_system_properties_get "bpy.types.TimelineMarker.bl_system_properties_get") - [`UIList.bl_system_properties_get`](bpy.types.UIList.html#bpy.types.UIList.bl_system_properties_get "bpy.types.UIList.bl_system_properties_get") - [`View3DShading.bl_system_properties_get`](bpy.types.View3DShading.html#bpy.types.View3DShading.bl_system_properties_get "bpy.types.View3DShading.bl_system_properties_get") - [`ViewLayer.bl_system_properties_get`](bpy.types.ViewLayer.html#bpy.types.ViewLayer.bl_system_properties_get "bpy.types.ViewLayer.bl_system_properties_get") |