1. An auxiliary view is an orthographic view which is projected onto any plane other than the frontal, horizontal, or profile plane. An auxiliary view is not one of the six principal views. One of the principle reasons for drawing auxiliary views is to show a surface at true size and shape.

2. An oblique drawing is a projective drawing of which the frontal lines are given in true proportions and relations and all others at suitable angles other than 90 degrees without regard to the rules of linear perspective.

3. Perspective Drawing is a technique used to represent three-dimensional images on a two-dimensional picture plane. In our series of lessons on perspective drawing we explain the various methods of constructing an image with perspective and show how these are used by artists and illustrators.

4. A blueprint is defined as a copy of a building or engineering plan, reproduced with white lines on a blue background, or detailed plan of action.