The flag in bNodePanel is anticipated to store settings such as whether a panel is open or closed by default. It's not currently used, so for now the flag is removed. The next_panel_identifier in bNodeTree is also not needed any more. It was used to set a unique identifier for each panel, which isn't needed. Added comments to remaining fields in bNodePanel. Pull Request: https://projects.blender.org/blender/blender/pulls/109028