Create a Document
Call the New() method to create a document.
A new document has an empty DocumentID value, thus the document is not accessible from the DocumentManager API. The ASPxSpreadsheet retains such a document until the control switches to another document.
The ASPxSpreadsheet generates a DocumentID value for the document when a user saves it to a file system. Alternatively, you can assign a GUID to the DocumentId property explicitly:
If the specified DocumentID value is not unique within all open documents, the ASPxSpreadsheet throws an exception. Call the GetAllDocuments() method to get identifiers of all open documents.