AFFILIATED PUBLICATIONS <AFP> TO BUY BILLBOARD Affiliated Publications Inc said it agreed to acquire all the outstanding stock of <Billboard Publications Inc> for 100 mln dlrs in cash from a shareholder group led by <Boston Ventures Limited Partnership.> Affiliated, which owns the company that publishes the Boston Globe, said the acquisition will give it a strong position in the growing market for specialty magazines. Under a separate agreement, Affiliated said that certain members of Billboard's management plan to buy up to 10 pct of the equity in Billboard following Affiliated's acquisition of the company. Billboard publishes eight specialty magazines, including Billboard magazine, and 15 annual directories. It also publishes and distributes speciality books under four imprints and operates two book clubs. Affiliated is the parent company of Globe Newspaper Co, publisher of the Boston Globe. It also has interests in cellular telephone and paging services providers.