В хелпе говорится, что кроме того, что Basic Graphics Layer является контейнером для всех Graphics Layers, он и САМ является Basic Graphics Layer, ТЕМ САМЫМ, который <Default>. Если тебе надо перебрать элементы в графическом слое, пиши нечто подобное:
Private Sub UIButtonControl1_Click()
Dim pMxDoc As IMxDocument
Dim pLayer As ILayer
Dim pDefaultContainer As IGraphicsContainer
Dim pContainer As IGraphicsContainer
Dim pBasicGraphicsLayer As ICompositeGraphicsLayer
Dim pGraphicsContainer As IGraphicsContainer
Dim pCompositeLayer As ICompositeLayer
Dim pElement As IElement
Dim pLyerCount As Long
'
Set pMxDoc = Application.Document
Set pBasicGraphicsLayer = pMxDoc.FocusMap.BasicGraphicsLayer
Set pLayer = pBasicGraphicsLayer
Set pCompositeLayer = pBasicGraphicsLayer
'
' Get the "Default" Annotation group
Set pDefaultContainer = pBasicGraphicsLayer
'Loop through all elements in Default Annotation group
ShowElementsGeometryType pDefaultContainer, pLayer.Name
'
' Loop through all another Annotation groups
For pLyerCount = 0 To pCompositeLayer.Count - 1
Set pLayer = pCompositeLayer.Layer(pLyerCount)
Set pContainer = pLayer
'Loop through all elements in Annotation group
ShowElementsGeometryType pContainer, pLayer.Name
Next
End Sub
Private Sub ShowElementsGeometryType(Container As IGraphicsContainer, LayeName As String)
Dim pElement As IElement
'
Container.Reset
Set pElement = Container.Next
Do Until pElement Is Nothing
MsgBox LayeName & ": " & pElement.Geometry.GeometryType
Set pElement = Container.Next
Loop
End Sub