auto-save-include-big-deletions

auto-save-include-big-deletions is a variable defined in `C source code'.
Its value is

nil

Documentation:
If non-nil, auto-save even if a large part of the text is deleted.
If nil, deleting a substantial portion of the text disables auto-save
in the buffer; this is the default behavior, because the auto-save
file is usually more useful if it contains the deleted text.