If you follow this rule for topographic maps, you can determine if a point is higher or lower than the contour line it is near:
a. if the point is outside the contour line, it is lower than the line. if the point is inside the contour line, it is higher than the line
b. if the point is outside the contour line, it is higher than the line. if the point is inside the contour line, it is lower than the line.
c. if the point is outside the contour line, it is equal to the lower line. if the point is inside the contour line, it is equal to the higher line.