The Zone system.

[Pacco J Pompei.]

The zone scale at right has ten steps and is based on Ansel Adams's description of zones in his book The negative. Zone 0(zero) relates to the deepest black print value that photographic printing paper can produce. Zone V corresponds to a middle gray, the tone of a standard-gray test card of 18 percent reflectance. Zone IX relates to the lightest possible print value-pure white of the paper base. The Zone System allows you to previsualize how the tones in any scene will look in a print and to choose either a realistic interpretation or a departure from reality. Using the Classic way to develop and expose your prints, and understanding the Zone System will help you get improved result in the final print stages.
This is why I use Color film to produce my Black and White Prints. Color film reacts to Black and White enlargement paper better than your average Black and White film. Color film records the colors as they appear, and Black and White film records tones, which are directly related to each tone scale. Color film gives greater details and contrast than black and White film.
I use the Zone System in my final print stages. This is where I can dodge and burn my details. My Photos are printed in Zones III to VII, it allows me to Hand Tint my Black and White Print with vivid or soft colors. The shades of gray intensifies the hue and tint of each color.