自定义的结构体如何取它的维数啊

自定义的结构体怎么取它的维数啊！
dim m_track() As Track 
ReDim Preserve m_track(1, 4)
Debug.Print UBound(m_track(1, 4), 1)



Public Type Track

  t_prn As String
  t_begin As UTCtime
  t_last As UTCtime
  t_xsx() As Double
  t_xsy() As Double
  t_xsz() As Double
  t_xssdt() As Double

End Type


------解决方案--------------------

VB code

  Dim m_track() As Track
  ReDim Preserve m_track(1, 4)
  
  ReDim Preserve m_track(1, 4).t_xssdt(5)
  
'  Debug.Print UBound(m_track(1, 4), 1)
  Debug.Print UBound(m_track(1, 4).t_xssdt)