I found Org-mode support file completion in `file:` prefix. But not `file+sys:`, Why?
- [ ] If it is not enabled by default. Then how to enable it? - [ ] If Org-mode does not support it, then how can I enable it? Why do I need it? When I add a link to a PDF file, I need to use filename completion, so I have to use `file:` completion, then use =[C-c C-l]= to edit the link again to add `+sys` for `file:`, this is painful.
