In the doc little is said about this number. Can we retrieve the entire arglist using this number and get all the versions of arglist?
Great question! The only existing use I can determine from the docs is that it allows you to find out whether a window is currently using a local
arglist or the global one.
However, it looks as though it's just the first step of some more extensive changes that allow you to use the number to manipulate the lists in use.
This code has already been written (see arglists.patch in this repository) but hasn't yet been accepted into the main Vim codebase: you can see it mentioned in
:help todo by searching for