This .NET class wraps the AcDbViewportTable ObjectARX class. 

ViewportTable is the symbol table for ViewportTableRecords, which represent viewport configurations within AutoCAD when the system variable TILEMODE == 1. Within AutoCAD and DXF files this symbol table is known as the "VPORT" table.

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.SymbolTable
        Autodesk.AutoCAD.DatabaseServices.ViewportTable

Public sealed Class ViewportTable
Inherits SymbolTable
Inherits IEnumerable

public sealed class ViewportTable : SymbolTable, IEnumerable;