[GreenKeys] Teletype code prefixes

[Jim Haynes]

It's rumored that the F prefix is to mean Fourteen.

Which rules out using it for Model 15, so the B prefix is said to
mean Bell

That makes one wonder if Model 12 has a Teletype code and what the
prefix was.

Now there's the venerable "iron horse" keyboard perforator GPE and
I suspect that the G comes from Green Code.  The early Teletype products
were Green Code, much like today's Baudot/Murray code, and made for
Western Union which had green as a corporate color.  There was also
the Blue Code used by Postal Telegraph which had blue as a corporate
color.  But if they had used B prefix for Blue Code machines they could
not have had it for Model 15.

Then there was a keyboard perforator coded DPE which was basically a
Model 19 keyboard perforator without a signal generator.  I'm guessing
that they wanted to eliminate the GPE product but the Model 28 perforator
was not yet ready for production.  So they could satisfy orders for the
GPE with the DPE, since Model 19 was still in production at the time.
I have no idea what the D stands for, if anything, and if there were any
other prducts besides the DPE.

The L prefix was used for both Model 28 and Model 35 since they were
basically the same design.  The distinction was made by starting the
Model 35 codes with an 8 for 8 level.  I have no idea what the L stands
for, if anything.  Similarly Model 32/33 uses the U prefix and the
8 for Model 33 versus 32.

We have the XD code for transmitter-distributor which I'm told was
considered part of the Model 14 line but then it was also used in Model 
19.  And there is the MXD for multiple-headed transmitter-distributors,
made in 3-headed and 6-headed versions for torn-tape switching.  And
FRXD for the Model 14 based typing reperforator part of that machine.
There was an LRXD which was a replacement for the FRXD, having the same
physical size and shape and functions but made with Model 28 machinery.
But more popular were the Model 28 "R-T stands" which held large tape
supply and takeup reels and a narrow form factor.

Now it's curious that the stock ticker using Model 37 technology is
called a Model 28 machine in Bell System literature.  Maybe they meant
to reserve Model 37 for more glamorous products.  I don't know if the
circa 1930 black cube stock ticker had a code prefix.  I'm pretty sure
it didn't have a model number, since the model numbers were Bell System
things.  And I never heard a model number associated with Inktronic.

Finally there were the V prefix codes, VCL and VSL.  Before these existed 
if you wanted a Model 28 KSR set you had to get a sales engineer to 
specify the LAC, LK, LP, LMU and LESU which would get you the typebox and 
keyboard layout and the stunt box arrangement.  In the early 1960s they 
realized that there were certain popular combinations that might as well 
be given a single code.  VSL was for a "system" or "set", which is to say 
a complete off the shelf ready to use set.  VCL was for a machine that was 
itself a component of some larger set or system.

 	---

 	"Ya can argue all ya wanna, but it's dif'rent than it was."
 	"No it ain't! No it ain't!  But ya gotta know the territory."
 		Meredith Willson, The Music Man