Some question about external method of elpa

[Feng Shu]

Hello everyone,

I have some questions about elpa external method, help is needed, thanks!

1. Does elpa cron auto call  "make external" or similar process to
   check out all the external packages?
   
2. If cron auto checkout external packages, does package author need
   manual-checkout?

3. Does subtree method have any advanced than external branch?
   if no, what about obsolote this method? In my opinion, subtree
   seem to very hard to manage.

4. I use subtree to manage posframe package, but I want to switch
   to  external branch method, how to work? what about create a
   subtree2external command?


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