sentences:  The bold lines of the diagram inclined by "α"b degrees are the base layer lines.The bold lines inclined by "α"r degrees are the revealing layer lines.The base layer lines are vertically spaced by a distance equal to "p"b, and the revealing layer lines are vertically spaced by a distance equal to "p"r. The distances "T"b and "T"r represent the true space between the base layer and revealing layer lines, correspondingly.