[GreenKeys] Yes, Virginia, there is a Model 15 Auto CR-LF

[greenkeys@mailman.qth.net]

You don't see it very often, probably most often on ex-military machines.
I have one here, and some but not all of the parts for the kit.  It
involves a sliding part across the front of the machine that is hit by a
little part attached to the type basket.  When that part slides to the
right it unblocks a function bar that trips both CR and LF.  There is also
a special CR function bar that trips both CR and LF, so if you get a CR
but not an LF you won't type over the same line again.

I presume this is something the military wanted for radio use, since in
RTTY you often get errors and losing a CR or LF is a big loss.