[NTG-context] issue field in bibliography

Hi, I have questions related with a journal named "Documentation photographque". Each issue is devoted to another theme. How should I declare this theme in bibliography fields when quoting articles? It is quite important to get it, because the main article is always named « Le point sur… » (I don't know exactly how to translate it in English. Something like "an overview of…") so quoting it makes only sense if the issue is named, at best after the title or the number. I thought issue may do it. Am I right? Or would be comment a better place? Best regards, Damien Thiriet