C# .NET - What is the Container in the below code

  Dim MemoryMapped As MemoryMappedFile = MemoryMappedFile.CreateFromFile(Application.StartupPath & "\Test.mdb", FileMode.Create, "MyMemMapFile", 1024 * 1024, MemoryMappedFileAccess.ReadWrite)
        Dim FileMapView As MemoryMappedViewAccessor = MemoryMapped.CreateViewAccessor()
        Dim Number As Integer = 1234
        FileMapView.Write(0, Number)
        FileMapView.Write(Of container)(4, mycontainer)




Please help me to know  what is container and what is it doing in the above.