The left table ('Qual') counts the types of qualifiers as defined in the first part of C13: Zonal Qualifiers. The right table ('Zonal') counts the players who qualified at a certain zonal ('z'), as listed in the second part of the same page.
The three players with an unknown qualification path (Qual = '?') -- Afifi, Bouaziz, & Hmadi -- all played in the 1985 Tunis Interzonal. Two of them qualified via African zonals and one was nominated by the Tunis organizers. I haven't been able to determine who qualified by what path.
The count for zone 4, the USSR, shows five players. GM M.Gurevich did not play an Interzonal although he qualified ahead of two other players. I haven't been able to determine why.
Later: To document a few discoveries, I added new clippings to C13: Zonals 1984-1987.