This question has been edited 47 times over a period of 23 days.
It started just as:
What is the difference between mask and umask?
I know that in *nix, a mask is any bit pattern used in bitwise operations (hence it is often called bitmask).
How it differs from umask? (user mask? unix mask?)
Now it has many more lines and many imprecisions which have been added progressively by its author.
It is impossible to hit a moving target.
I have tried to answer twice and both answers have been rendered inaccurate by additional modifications to the question.
Should there be a limit to the amount of change?
I understand that it is very difficult to draw a line in a general sense. Each case is different. But this case should be an extreme example.
Editing a question should, in general, be avoided.
Specially if it is to answer it.
Should a moderator have block further edits? Maybe.
Should the user have been told the problem he was generating with a "moving target"? Probably yes.
What should a user do instead:
Provide his own answer.
- An answer should be edited to make it better, by anyone.
- Could be edited as much as needed to correct imprecisions.
- It doesn't invalidate other (previous) answers.
- The OP could also edit and improve his answer.