Context and archived or completed dropped tasks

OmniFocus
#1

Hello

I will change or delete some contexts in current OF.
I have some archived and completed tasks, also the backups.

Question 1
When I change or delete the contexts in current working OF what are the consequence in archived and completed tasks?

Question 2
When I change or delete the contexts in current OF what are the consequence in backup files?

Question 3
When I change or delete the contexts in current OF what are the consequence in backup files when I open a backup?

Jochen