Modern accounting and inventory management systems let users keep track of multiple issues or articles - multitudes of goods for sale, invoices, purchase orders, you name it. From this perspective, anything you account for is a separate article of a particular type. Each individual type of merchandise is thus nothing more than one of such articles in a particular category being tracked. That said, I have no idea whether my own interpretation above is the accepted current Russian usage. Hopefully, someone can do better.

"АРТИКУЛ (от лат. articulus - раздел, статья) - торговый термин, означающий тип товара и его цифровое и буквенное обозначение"
(c) Экономический словарь

(ссылку, извините, почему-то система отвергла :))