[Browsable(false)]
public IWorkbook Document { get; }

<Browsable(False)>
Public ReadOnly Property Document As IWorkbook

using DevExpress.Spreadsheet;
// ...

// Access a workbook.
IWorkbook workbook = spreadsheetControl1.Document;

Imports DevExpress.Spreadsheet
' ...

' Access a workbook.
Dim workbook As IWorkbook = spreadsheetControl1.Document

{
    IWorkbook workbook = spreadsheet.Document;
    foreach (Worksheet sheet in workbook.Worksheets)

{
    IWorkbook workbook = spreadsheet.Document;
    foreach (Worksheet sheet in workbook.Worksheets)

{
    IWorkbook document = spreadsheetControl.Document;
    document.BeginUpdate();

spreadsheetControl1.LoadDocument("Documents\\MailMergeTemplate.xlsx");
template = spreadsheetControl1.Document;
template.MailMergeDataSource = dataSet;

#region #SetEncryptionTypeAndPassword
IWorkbook workbook = spreadsheetControl1.Document;
workbook.DocumentSettings.Encryption.Type = (EncryptionType)Enum.Parse(typeof(EncryptionType), barEncryptionTypeComboBox.EditValue.ToString());

Private Sub evaluator_OnAfterCompile(ByVal sender As Object, ByVal args As OnAfterCompileEventArgs)
    Dim workbook As IWorkbook = spreadsheet.Document
    For Each sheet As Worksheet In workbook.Worksheets

Private Sub evaluator_OnAfterCompile(ByVal sender As Object, ByVal args As OnAfterCompileEventArgs)
    Dim workbook As IWorkbook = spreadsheet.Document
    For Each sheet As Worksheet In workbook.Worksheets

Private Sub evaluator_OnBeforeCompile(ByVal sender As Object, ByVal e As EventArgs)
    Dim document As IWorkbook = spreadsheetControl.Document
    document.BeginUpdate()

spreadsheetControl1.LoadDocument("Data\MailMergeTemplate.xlsx")
template = spreadsheetControl1.Document
template.MailMergeDataSource = dataSet

#Region "#SetEncryptionTypeAndPassword"
            Dim workbook As IWorkbook = spreadsheetControl1.Document
            workbook.DocumentSettings.Encryption.Type = CType([Enum].Parse(GetType(EncryptionType), barEncryptionTypeComboBox.EditValue.ToString()), EncryptionType)