How to detect auto-dimensions?

The code below shows how to tell the difference between a driving dimension, a reference dimension, and an auto dimension.

Option Strict Off
Imports System
Imports NXOpen
Imports NXOpen.UF

Module SketchAutoDim

Sub Main()

Dim theSession As Session = Session.GetSession()
Dim workPart As Part = theSession.Parts.Work
Dim theUfSession As UFSession = UFSession.GetUFSession()
Dim lw As ListingWindow = theSession.ListingWindow
lw.Open()

For Each objSketch As Sketch In workPart.Sketches
objSketch.Activate(Sketch.ViewReorient.False)
lw.WriteLine("sketch: " & objSketch.Name)

Dim sketchDimTags() As Tag
Dim numSketchDim As Integer
theUfSession.Sket.AskDimensionsOfSketch(objSketch.Tag, numSketchDim, sketchDimTags)

lw.WriteLine("number of dimensions: " & numSketchDim.ToString)

Dim numDriving As Integer = 0
Dim numRef As Integer = 0
Dim numAuto As Integer = 0

For Each temp As Tag In sketchDimTags
Dim expTag As Tag
Dim expString As String
Dim expValue As Double
Dim status As Integer
theUfSession.Sket.AskDimStatus(temp, expTag, expString, expValue, status)

Dim refStat As UFSket.ReferenceStatus
theUfSession.Sket.AskReferenceStatus(objSketch.Tag, temp, refStat)

'auto dimensions are active, but have no expression
'associated with them
If refStat = UFSket.ReferenceStatus.Reference Then
numRef += 1
Else
If expTag = Tag.Null Then
numAuto += 1
Else
numDriving += 1
End If
End If

Next

lw.WriteLine("number of driving dimensions: " & numDriving.ToString)
lw.WriteLine("number of reference dimensions: " & numRef.ToString)
lw.WriteLine("number of auto dimensions: " & numAuto.ToString)
lw.WriteLine("")

objSketch.Deactivate(Sketch.ViewReorient.False, Sketch.UpdateLevel.SketchOnly)
Next
lw.Close()

End Sub

Public Function GetUnloadOption(ByVal dummy As String) As Integer

GetUnloadOption = NXOpen.Session.LibraryUnloadOption.Immediately

End Function

End Module