Add a new subcategory into the Autodesk Revit document. 
   Namespace:   Autodesk.Revit.DB  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
Syntax
| C# | 
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| Visual Basic | 
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| Visual C++ | 
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Parameters
- parentCategory
-  Type:  Autodesk.Revit.DB Category  
 The parent category.
- name
-  Type:  System String  
 The new category name.
Return Value
If successful, the newly created subcategory.Examples
 Copy  C#
 Copy  C# public void AssignSubCategory(Document document, GenericForm extrusion)
{
    // create a new subcategory 
    Category cat = document.OwnerFamily.FamilyCategory;
    Category subCat = document.Settings.Categories.NewSubcategory(cat, "NewSubCat");
    // create a new material and assign it to the subcategory
    ElementId materialId = Material.Create(document, "Wood Material");
    subCat.Material = document.GetElement(materialId) as Material;
    // assign the subcategory to the element
    extrusion.Subcategory = subCat;
} Copy  VB.NET
 Copy  VB.NET Public Sub AssignSubCategory(document As Document, extrusion As GenericForm)
    ' create a new subcategory 
    Dim cat As Category = document.OwnerFamily.FamilyCategory
    Dim subCat As Category = document.Settings.Categories.NewSubcategory(cat, "NewSubCat")
    ' create a new material and assign it to the subcategory
    Dim materialId As ElementId = Material.Create(document, "Wood Material")
    subCat.Material = TryCast(document.GetElement(materialId), Material)
    ' assign the subcategory to the element
    extrusion.Subcategory = subCat
End SubExceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentNullException | Thrown when the input argument-"parentCategory" or "name"-is a null reference ( Nothing in Visual Basic) . | 
| Autodesk.Revit.Exceptions ArgumentException | Thrown when the input argument-"parentCategory"-cannot add subcategory. Thrown when the input argument-"name"-is an illegal name. | 
| Autodesk.Revit.Exceptions InvalidOperationException | Thrown when subcategory creation failed. |