## Add(*[CustomXmlPart](../../customxmlpart/)*) {#add_1} Adds an item to the collection. ```Csharp public void Add(CustomXmlPart part) ``` | Parameter | Type | Description | | --- | --- | --- | | p...... ```csharp public void Add(CustomXmlPart...tag with custom XML data. ```csharp Document doc = new Document();...