pr-auto-region

pr-auto-region is a variable defined in `printing.el'.
Its value is

t

Documentation:
Non-nil means region is automagically detected.

Note that this will only work if you're using transient mark mode.

When this variable is non-nil, the `*-buffer*' commands will behave like
`*-region*' commands, that is, `*-buffer*' commands will print only the region
marked instead of all buffer.

You can customize this variable.