version-control is a variable defined in `files.el'.
Its value is
nil
This variable is safe as a file local variable if its value
satisfies the predicate which is a byte-compiled expression.
Documentation:
Control use of version numbers for backup files.
When t, make numeric backup versions unconditionally.
When nil, make them for files that have some already.
The value `never' means do not make them.
You can customize this variable.