This .NET class wraps the AcDbSection::Height ObjectARX enum. 

It gives the height of the section plane above or below the section line. The returned height is the indicator height when the section plane type is either plane or boundary, since the cut extends infinitely in the vertical direction for these two types. The height of the cut is returned when the section plane type is volume.

Public Enum SectionHeight
  HeightAboveSectionLine = 1
  HeightBelowSectionLine = 2
End Enum

public enum SectionHeight {
  HeightAboveSectionLine = 1,
  HeightBelowSectionLine = 2
}