Yes Halftones. You need a magnifying glass. That gray on the right side of the page is actually black dots. The bigger the dots the darker the gray, or the more dots the darker the gray. The blue picture on page 402 is one color. The darker color has more dots than the lighter color.
The young lady on page 262 is made of four color dots. Cyan, magenta, yellow and black (CMYK). In PageMaker or Indesign I could enter the number of dots per inch and the angle; and print the separations (4 pages of black dots, CMYK). From this the printing company would make his four plates. Today I email a file of the separations to the printing company.
Wikipedia explains this much better than I can. Just type in CMYK.
There are fewer printing companies around these days. I can't afford Adobe.
I don't print. I provide artwork; the negative used to make the offset plate (so to speak). In page 345 of the Publisher Workbook; the right side of the is printed in black ink. There is no gray ink on the page. Only halftones. Tiny black dots that appear gray because of the white background. That is what I am trying to do. Help me.
By the way the whole Publisher Workbook is is printed using CMYK with some spot colors. I can do that using Adobe products. Can this be be done using Affinity products.