Projection Lines, Dimension Lines and Leader Lines:

Projection lines, dimension lines and leader lines are drawn as thin continuous lines displayed.

(a) Projection lines shall extend slightly beyond the respective dimension line.

(b) Projection lines shall be drawn perpendicular to the feature individual dimensioned. Whereas, conversely essential, they may be drawn obliquely but parallel to each other. 

(c)   Intersecting projection and construction lines shall extend slightly beyond their point of intersection.

(d)   In common, projection dimension and lines must not cross other lines unless this is unavoidable.

(e)   In common, projection dimension and lines must not cross other lines unless this is unavoidable.

(f) Intersecting dimension lines and projection should be avoided. Where unavoidable, however, either line shall be displayed along with a break.

(g) A centre line or the outline of a part shall not be used as a dimension line however may be used in place of a projection line.