If you are creating a new subscription at serials/subscription-add.pl and click the link to "create biblio," the add biblio process happening in that pop-up window isn't tailored to the subscription create process. Ideally, after saving the new biblio the window would close and the subscription add form would be populated with the new biblionumber. I assume this would have to be done by passing a parameter from the add subscription page so that the addbiblio.pl save process can be redirected.
This is still valid for current master.
Still an issue?
I just tested this and the biblionumber was not sent back to the form when closing the window. 1) Add new subscription 2) Create record link 3) Downloaded a record from Z39.50 4) Fixed errors 5) Saved 6) Went to item form, instead of closing 7) Closing window manually - biblionumber remains empty. If this is not supposed to work, maybe we should open the cataloguing form in a new tab instead.