All types of annotation for Autodesk Civil 3D elements are governed by label styles, which are objects of type LabelStyle. A label style can include any number of text labels, tick marks, lines, markers, and direction arrows.
The following example creates a new label style object that can be used with points:
CivilDocument doc = CivilApplication.ActiveDocument; ObjectId labelStyleId; labelStyleId = doc.Styles.LabelStyles.PointLabelStyles.LabelStyles.Add ("New Point Label Style");