>>However, the graphic artist was more likely to have had them available on his/her computer — as “crop marks”: <<
Actually, the crop marks are the long lines to tell where to trim.
The surveyor symbols in your example are called “registration marks” and are used to align overlays (the way we did things in the old days for what we called “process jobs” — 4 clear acetate overlays to get full color).
I used to own an ad agency and we did all that kind of stuff. Pica poles, Xacto knives, wax and screens (I think I still have a pica pole around here somewhere...). Manual kerning... wow, now that I look at what you can do with MS Word and Photoshop I am amazed we were able to produce anything at all. If you were to go back to our shop then, it would be like vising Fred Flinstone...
I know what you mean about tech advances: At TI's SRDL in 1965, I drew my first ECL IC layout on grid paper, copied the coordinates off onto an 80-column form, keypunched the cards, used them to produce a plot on a CalComp plotter, and then took the plot to the "Zip-cutter" guys who used a manual X-Y rig to cut the "Ruby-Lith" -- and then peeled off the red stuff by hand.
Then I had to check their work by eyeball (patching mistakes with red tape) -- without getting fingerprints on it. Then it took several weeks to get masks back from the mask-making vendor...
(I'm not going to admit how many times I had to re-punch cards before the CalComp plot finally matched my original...) ;-}
Again, thanks for "sorting me out!" '-)