is a variable defined in `
C source code
Its value is
global value is the same.
- Automatically becomes permanently buffer-local when set.
Length of current buffer when last read in, saved or auto-saved.
-1 means auto-saving turned off until next real save.
If you set this to -2, that means don't turn off auto-saving in this buffer
if its text size shrinks. If you use `buffer-swap-text' on a buffer,
you probably should set this to -2 in that buffer.