Given the lack of direct information, the best approach is to ask the user for clarification. They might be referring to a self-published work, an academic paper, or a niche publication. It's possible that "vol13 20_upd" is part of their internal version control system, like a draft number. Alternatively, the "20" could relate to a chapter or specific section within the volume that's been updated.
Given the lack of direct information, the best approach is to ask the user for clarification. They might be referring to a self-published work, an academic paper, or a niche publication. It's possible that "vol13 20_upd" is part of their internal version control system, like a draft number. Alternatively, the "20" could relate to a chapter or specific section within the volume that's been updated.