The Monotype code system

[John Cornelisse]

Controlling the width of a character cast on a Monotype composition-caster.

Monotype did built a quite complex system to control the width of characters and spaces.

The whole system was based on wedges, the position of the individual wedges determined how far
the mould could be opened to receive the molten metal. After this the matrix was pushed against the
seating of the mould, and the pump could do its work.

The matrices were placed inside the diecase in rows of equal widths. The layout of the diecase was
designed according the unit-arrangement or UA, a list of all unit-widths of the characters of the font. 

The composition caster was an automatic machine, texts were cast in composition controlled by a mechanism
using compressed air and punched ribbons. These ribbons were typed on special keyboards. These keyboards
used standard qwerty-layouts, and extra equippement keybanks and more depending the actual font used for the text.

Definitions: Set, unit-width, Unit-Arrangement

SET

In order to limit the number of widths for characters, the set-system was made.

Definition: set = the width of the widest character measured in 1/4 pica points.

Example: In Bembo series 270-13 is 11 set: the width of the W is 11 pica points or 11 * 1/6 * 1/12 inch (old pica)

........

There is one 'little' complication here:

In the UK and the America's the pica is defined by: 1 pica = .1660 inch.
On this NEW pica all wedges used un the UK and America & Canada are based.

However ALL wedges used at the European continent were based on the OLD pica: 1 pica = 1/6 inch = .1667 inch.

Wedges were grinded at a precision of 1/10000 of an inch, or 10000 dpi !

This contributes to minor differences between the UK and continental manuals and tables.
Hardly noticable for a single character, but when casting lines these little differences will add up.
So a user should be aware of the wedge used... however from the marks on a wedge this cannot be identified.

To keep things a bit simple I will use the OLD pica in this story.

Some old-pica wedges:

S5-12 set, 277-10 set, 467-10 set, 562-10 set, 562-10 3/4 set



.......

Definition: unit-width

1 unit = set-width / 18

for 11 set this is  11 * 1/6 * 1/12 * 1/18 = 11 /(6*12*18) = 11/1296 =  .008489 inch  (or .00845 inch for the new pica)

All character were designed to have a whole number of unit widths:

4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 units, or even more.

9 units 11 set = 9 * 11 / 1296 = .0764 inch
18 units 11 set = 18 * 11 / 1296 = .1528 inch

old pica: 12 set = .1667 inch



new pica: 12 set = .1660 inch



Unit arrangement

The scedule of all widths of the characters of a font is called: unit-arrangement.



With this data and the unit-values of the rows of the wedge it is possible to design an arrangement ot m.c.a.
for the diecase of this font. 

To keep operations as fast as possible, the most used characters are placed on at a row, where they will be
cast at the proper width without extra correction.

MCA Poliphilus en Blado



Note: All permutations at one row will result in a proper result: the mats can be cast in composition.

In the old hot metal days however, with the layout came also the extra equipment - two keyboard-banks -  for
the keyboard. The American brand had a limited number of layouts, minimizing costs for the customer.

Monotype Corporation Lim. in the UK had a different approach: Numerous layouts were made.

All "custom"-made for the user. Of course all those European or non-English languages have all those
peculiar accents, and these eXtra matrices make it extra complicated.

But even for a typeface like Times New Roman, the face that every printshop had, I never found equal
layouts for different printers.

[John Cornelisse]

Coding on Monotype Composition casters

The papertower of the composition casters has 31 positions for the code that controls the actions of the machine.

In the early days of Monotype these positions were named with the numbers 1 to 31. Later machines use
character-codes:

At the keyboards two more marks are found:

                                                              0                                                                                              0
0   N  M  L  K  J   I   H  G  F   S   E    D    0    C   B   A   1    2   3   4    5   6   7   8    9   10  11 12 13 14  0  15
                                                              7                                                                                              0
                                                              5                                                                                              5
0   1  2   3   4   5  6  7  8   9  10 11 12 13 14  15 16 17 18 19 20  21 22 23 24  25 26  27  28 29 30  31 32

The keyboard-mechanism depends on a balance-mechanism.

One valve at the back is constant activated, and the punches and the papertransport would only operate when
at least two punches were activated. Because of this the mechanism has two idle punches, O and 15, these punches
do lift themselves, but don't make a hole in the ribbon line because they are shortened.

The code-lines on the ribbon can contain: 0, 1, 2 up to 5 or more holes, depending of the attachments present at the machine.

Decoding the ribbon.

         

One line Monotype-code (on a unit-adding machine)

         

The first Monotype composition casters used matric-cases with 275 matrices,

15 columns coded with A, B, C, D, E, F, G, H, I, J, K, L, M, N, O,
15 rows coded with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15.

15 * 15 diecase:

           

Later machines had 2 extra columns positioned at the left side of the matrix-case, coded with NI, NL: 17*15-machines.

A third development was the arrival of 17*16 diecases.

For this there were several coding-systems:

  - Unit-shift and
  - MNH-machines.

The last machines used special wedges with 16 positions, the mat-case moved also an extra row further. This last row was reached with a two- or three-character code.

unit-shift

           

MNH:

           


Controlling the width of the character cast

Monotype had some 6 different mechanisms to adjust the width of a character to be cast:

a) the normal wedge
b) single justification
c) double justification
d) casting high spaces
e) unit shift
f) unit adding


A) The normal wedge

This wedge makes in one direction the same movement as the die-case.

The wedge will stop the movement of the mould blades according the position of the wedge.

A wider character are cast with the narrow areas of the wedge. At the rows of the wider characters
the wouldblades can open more, because there the wedge will stop the blades at a later moment.

A small character in the first row will be cast with the widest part of the wedge. Consequently the
mouldblades will be stopped earlier, and the character will be cast at the proper width.

There have been a series of wedges. But there was also a standard wedge: marked with S5.

The unit values of the rows for this S5 wedge are:

    5 - 6 - 7 - 8 - 9 - 9 - 9 - 10 - 10 - 11 - 12 - 13 - 14 - 15 - 18

Each wedge is designed to fit a particular set: the set of the wedge need to be equal to the set of the font.
Otherwise all character would be cast too wide or too narrow.

S5-wedges

         

NOTE: the E next the the set-number:

These wedges are OLD-pica wedges ! I'm living in Holland, at the continent. I just learned
old-pica wedges are marked the way.

Old pica   12 pica-points = .1667 inch
New Pica 12 pica-points = .1660 inch


B) Single justification

The position of the two justification wedges are controlled with the codes:

0005 - b (b = 1-15)

This code has a number of functions:

       1) the pump is turned off (permanently)
       2) the 0005-wedge is replaced to position b

0075 - a (a = 1-15)

this code will act:

       1) replaces the coarse 0075 wedge to position a
       2) the pump is put into action, the next cycle a character will be cast

After this the next character or space will be cast combined with the S-code.


C) Double Justification

The position of the two justification wedges are controlled with the codes:

0075 - 0005 - b  (b = 1-15)

This code has a number of functions:

       1) no pump action
       2) the 0005-wedge is replaced to position b
       3) the 0075-wedge is replaced to position b
       4) the galley-mechanism is switched on:  during the next 7 machine-cycles the line is put
            to the galley

0075 - a (a = 1-15)

the actions of this code are:

       1) no pump action
       1) replaces the coarse 0075 wedge to position a
       2) the pump is put into action, the next cycle a character will be cast

After this all codes containing an S-code will be cast using the adjustment wedges.

This is called Double justification, because the 0075-wedge is moved twice, first to the
position of the 0005-wedge, and than to its proper position.


Calculating the correction:

The position a/b can be calculated with the following procedure:

1)  3/8 is called the neutral position.

this means: 0075-wedge at position 3, and the 0005-wedge at 8.

Each figure larger will add .0075 inch for the 0075-wedge, and .0005 inch for the 0005-wedge.
One position change for the 0075-wedge equals 15 movements of the 0005-wedge.

The smallest position 1/1 will take away 2*.0075 + 7*.0005 = .0185 inch (= 2 units 12 set)

The largest addition possible is: 15/15 => 12*.0075 + 7*.0005 = .0935 inch (=10.1 unit 12 set).

This is a lot more than could be taken away. In fact with the wider character the mouldblades could be
wider than a 0.2 inch wide matrix. And the cast would end up in a splash.


example 1, single justification:

adding 2 units 11.25 set to a character at G7

2 unit 11.25 set = 2 * 11.25 / (6 *12 *18) =  .01736 inch
this equals 34,7 steps of .0005 inch: rounded: 35
neutral position 3/8 =  3*15 + 8 = 53   
53 + 35 = 88 = 5 * 15 + 13 = 5/13
placing the adjustment-wedges at 5/13 will add 2 units 11.25 set

After the next code sequence, the character at G7 will be cast 2 units wider:

13 - 0005
0075 - 5
GS7


example 2: double justification

line with 9 variable spaces at G2, 5 units 13.25 set left over

5 units 13.25 set = 5 * 13.25 = .051119 inch
devided over 9 variable spaces: .051119 /9 = .00567 inch * 2000 = 11
53 + 11 = 64 = 4 * 15 + 4 => correction = 4/4

After the next code sequence all variable spaces cast with GS2 will fill the line:

0075 - 4 - 0005
0075 - 4
all variable spaces are cast with: GS2         


example 3: double justification

line with 7 variable spaces at G2, 4 units 9.75 set needed to get "lost"

-4 * 9.75 /1296 = - 0.030092 inch * 2000 / 7 =  - 8.597 =  - 9
53 - 9 = 42 = 2 * 15 + 12 => 2/12

code sequence:

0075 - 12 - 0005
0075 - 2
all variable spaces in the line are cast with: GS2         

The next two tables are based at the new-pica 12 set = .1660 inch

       

       

[mmckenzie]

Dear John.

Thank you for a most informative article. 

I am now the proud owner of a Composition Caster and Super Caster from Harry McIntosh (he stresses that he has not retired and is still casting!)

I'm using his interface, currently with my own software producing an intermediate file which is then "punched" by his software that goes with his interface.  I am, nevertheless, contemplating building my own interface and so have been musing over the very coding rules that you describe.

Matt
http://paekakarikipress.com

[John Cornelisse]

Dear Matt,

I must add, that this two posts are just a start - although they are already quite long.

This is far from complited, Ill try to do this within a few weeks.

My polish friend has made his prototype interface. It works quite well. And now he is struggling with the programming. My source... I;m Dutch so a lot of names are just dutch,,, No problems with reserved words at all. The plan is to reprogram my own source,

My present program runs under MSdos. No problem with that, but in the end I will need a more modern computer too.

Best wishes

John

[John Cornelisse]

d) casting high spaces

Suppose a certain mat is 16 units wide, but there is only room for this mat at the row
with 11 units. When this mat is cast, the result will be a overhanging chracter.

5 units are missing.

The character will be completed after a high space of 5 units is been cast. This high space
is cast from a blank mat in the 5-unit row , with a normal hole for the center-pen.

The high space will support the overhanging character.

Very wide character like the combination series-119 Qu need 32 units, this accomplised
with a 17 unit cast followed with a 15 unit high space. Made with a blank mat in the row with 15 units.

An equal result could be obtained with 3 cast of a 5-unit high space.


e) unit shift

Unit shift was introduced around 1960. There was some need for larger diecases. A 16th row
was added to the diecase. The wedge kept its 15 positions.

Mats in the 16th row were cast with an extra movement of the diecase. The wedge kept its
position, and the mat was cast still at 18 units of the set.

All other mats, except the mats in the first row, could make this movement too. With this
system it was possible to use a wedge with only one row of 11 units, even when there was
a need for two rows 11 units.

Another advantage - for Monotype only - was the extra freedom to arrange a MCA for a client.
Optimizing the profit of the enterprise ...

The code of the machine was altered:

(corrected text : 19 jan 2015)

             replacing the 0005-wedge:     0005 
             replacing the 0075-wedge:     0075
      activating the galley-mechnism:    0075 + 0005
             D = unit shift
             EF = place the matrix-case in the D-column
             
the code FE4 will cast the character at D4 at 8 units using the S5-standard wedge
the code FED3 will cast the character at D4 at 7 units using the S5-wedge


There was yet another system for 16*17 diecases: NMH.

Here the diecase could also move another position extra, but only the 16t row.
This system used special wedges with 16 positions. The colums of the 16th row
were coded with a 2 or 3 character code/ This system will be explained later.


f) unit adding

This system uses extra little wedges, when activated the transfer-wedge will
make an extra movement forward. And the mould blade will open 1, 2 or 3 units of
the set more, depending on the thickness of the little wedge.

             replacing the 0005-wedge:    0005 => NJ
             replacing the 0075-wedge:    0075 => NK
       activating the galley-mechnism:   0075 + 0005 => NKJ
             unit adding:                            0075 added to the code
             0005  no action

These wedges are rather difficult to position in the machine. And the same result
can be obtained with single justification.

The only problem with this is mixing single justifacation with variable spaces. The width
of variable spaces is adjusted at the beginning of the line, when the proceeding line is sent
to the galley, and the next code when the 0075-wedge is replaced.

Using single justification for a certain character will set the adjustment wedges in another
position. The next variable space would be cast with the new corrections.

...............

Of course it is possible to combine the Unit-Adding-attachment with Unit-Shift,.

On both my machines these two attachments are actually present.  But both are not used: I rather use 15*17 diecases.

                       

This is a photograph of the Unit-Adding Attachment on my own machine.

NOTE: the black switch is in the OFF-position. Back to the old coding system.

...................

The ribbons I got at first were my only source of information. And in these ribbons actually each code 0005
was accompagnied with NJ, and each code 0075 with NK.

(Much later I heard that a keyboarder could provoke this, leaving a switch in a wrong position.
For the caster-operation this had no ill effect at all.)

I went to Max Stiebner, one of the former directors of Monotype Corporation Amsterdam.
I hoped he could explain it a little. But with all his experience with the machines he could
not tell me a lot about it.

Or did he kept his knowledge for himself as he did in other occasions ? Like how to
change a machine from english/french height to Dutch height... He was the only man
in Holland who ever did this kind of operations during the commercial life of Monotype.

I'm not sure about it. He lived some 102 years, and I kept contact with my old friend
until a few months before his death.

...............

With a computer-program it is however possible to add extra single justification code
whenever needed.

a) the initial position of the 0075 & 0005 wedges is stored in two variables

           var_sp_0005 = b
           var_sp_0075 =  a

     two extra variables are used to store the actual position of the wedges

           actual_0005 = b
           actual_0075 = a

b) whenever a GS2 or maybe GS1-code is found

           the program does ask itself:

      (var_sp_0005 == actual_0005 ) && ( var_sp_0075 == actual_0075 ) ?

           when this is not the case extra code needs to be added:

           0005 - b
           0075 - a

c) casting a character with single justification

when a character needs single justification, this code is present in the file.

This code might be needed, or might not be needed: whne several character with
the same correction would be casted after each other. The wedges are placed in the
right place before the first character is cast.

The code present in the file for the next character can be omitted :

The program can control this with:

         contains the code a 0005 code ?
                 
        - yes:
                  store value 0005 : corr_0005 = d                     
                  read the next code
                  store value 0075 : corr_0075 = c

                 (corr_0005 == actual_0005 ) && ( corr_0075 == actual_0075) ?
                      NO:
                      cast: 0005 d
                      cast: 0075 c
       - no:
                  cast code

Programming the code for the machine:

I use two programs  a translator and a caster-controller called Dump

1) the translator

The input is an ascii file, plain MSdos.

I do not like all those strange formats, a program like Word  is a disaster and other text-file
formats are just a big disaster, and often changed too.

I use Word-pad or Note-pad and store my texts as plain ASCii-files.

This translator program produces two files:
       a) the monotype code file extintie .cod
       b) an ascii text-file with the a readable result

The ascii-file is enriched with command codes, three character long.

All command codes start with: ^

Whenever a ^-sign is found, the next two character will be interpreted by the program, and
when the combination is not in the list, the two chars will be ignored:

         ^00  = all chars from now are ROMAN
         ^01  = italic
         ^02  = small capitals
         ^03  = bold
         ^04 = superior
         ^05 = inferior

end of line or paragraph:

^CR = white at the right site
^CC = text centered
^CL  = white left
^CF  = flat line: filled spaces

kerning:
     
        ^+a  = add a units       (a=1-2,3,4,5,6,7,8,9,a,b,c,d,e,f)
        ^-b  = take away b/8 units  (b=1,2,3,4,5,6,7,8)

This summery is by far not complete. It is possible to add codes for special character
using the hexadecimal-coding of the standard table for ascii-codes:

for example: ^80  is C-cedille,  ^87  is c-cedille

2) Dump

This program can read the code-file and sent it to the interface and the composiition caster.

It has lots of other functions:

          - adjusting the machine
          - controlling the 3/8 adjustment for the adjustment wedges
          - centring the die-case at G8
          - setting the set-width of the wedge
          - adjusting the lining of the diecase
          - casting single character for cases
          - testing the action of the valves

[John Cornelisse]

A little booklet I just found had more precise information:

The original machines used:

0075 : replacing the 0075 wedge
0005 : replacing the 0005 wedge
S       : activating the adjustment wedges
0075 + 0005 : line to the galley

Unit Adding - machinnes:

NK: replacing the 0075 wedge
NJ : replacing the 0005 wedge
S   : activating the adjustment wedges
NJK : line to the galley

0075 -> unit adding
0005 -> Tow-colour or Mathematical attachment

Signalled leading attachment

The S could be combined with 0005 for the justification cades.

This combined signal was to trigger off the signalled Leading mechanism.

Line Kill

A 0005-signal will halt the casting, this will only be released by a 0075-code

Line-kill was not appreciated by the caster-operators: the casting stopped, and after 10
or more idle machine cycles, the mould is cooled down.

15*17 -attachment

The extra rows are coded with NI and NL

Unit-shift

The D-row is coded with EF

D will force the diecase to move one row extra.

Of course Unit shift can be combined with unit-adding.

Later more... about the MNH-16-17 attachment.

[John Cornelisse]

The MNH-attachment

           

Above matrix-arrangement with 17 * 16 matrices contains all codes for the MNH-attachment.

Row 1 to15 can be reached with the normal coordinates. NI,NL,A-O. combined with the proper number.

The 16th row can be reached with the following codes:

*  columns NI and NL  + H,
*  columns A - G          + HM
*  column   H               + N
*  columns I - N           + HM
*  column   M               + H
*  column   N               + M
*  column  O                + HMN

When these codes - with only characters ! -  are met, than the MNH-meachanism will let
the piston drop of the 15th row drop. This piston limits the movement to 15 poistions, but now
the air to this piston is cancelled.

And the diecase and the wedge - the two of them will move one row further.

These wedges have 16 positions, because of this.

These attachments were quite rare. But to my surprise both machines in my workshop have this MNH-thing...

Anybody who knows a 17*15 machine, will notice the different arrangement for this particular attechment.
The two attachments are fitted together.

           

The big block has three valves that will lift the plate, their combined action determins
the mat and the column that will be cast.

Other available attachments will complicate the code further of course. Combining this with
unit-adding, (also present on my machines !) will change the codes for single and double justification
according in NK, NJ, NKJ. Combining with unit-shift is also not forbidden. (and of course... also
present on my machines)

With the possibility of single justification and a computer-program, I never felt the need
to use these two attachments.


Unit-Shift-attachment

The next MCA is designed for unit-shift.

             

The characters with a stripe above them, will be cast at the width of the row above.

The wedge needs the correct numer of the row.

Example:

DC9 will yield: h cast at 10 units,  C9 will give u=small capital also 10 units

EFD14 will give U at 15 units

[John Cornelisse]

Single justification

                       

The ribbon is performed down wards.

GS3  var space 
O15 = 17 units
GS3  = var space

S-14-0005 = 0005 wedge to 14
S-0075-7   = 0075 wedge to 7

MS2   = character cast:  .0335 inch wider 7/14 - 3/8 = 4/7 => 4*.0075" + 7*.0005"

The next character complete the word:

B3, H2, F1, K7, B3, G2

G2 is a fixed space, in poems used to keep all spaces equal.

L4, I9, K2 = next word

G2.......

Double justification

                       

Here we see the start of a line with variable spaces followed by a 17 unit square
cast at O-15, however these variable spaces are actual cast at 3/8, so in fact there
is nothing added, and the S could have been omitted.

Unit-shift

With the help of David Bolton, I found also a little piece of ribbon, with unit-shift code. He
did include in his last contribution for the LEG-group.

                       

We find the code EF-2 just before the double-justification code.

There the line will be brought to the galley, and the new line will be cast.

All variable spaces GS2 will be cast at the 6/9-correction.


Single Justification without the proper wedge

The next ribbon is a little part of long text I made for a job to cast a large composition diecase with 16pt Bembo,
without the proper wedge, I even had to use a wedge of another set: S5-13E, while Bembo-170-16 is 13,5 set.

So at either change of a row, single justification is needed.

Casting in this way slows down the action of the machine, but with these large sizes, the machine needs to be slowed down anyway.

The ribbon reads from the bottom, and after a few codes a double justification is met. After this the play restarts.


                           

conclusion: Monotype had a very flexable system, far more flexable than they ever thought it to be.

[John Cornelisse]

Monotype made all kinds of attachments for the machine. Complicating the code, but I found that the original coding system was very versatile.

Actually all those clever attachments, I do not use them at all.

No Unit Adding, because I do not have all the proper little wedges, and placing them in the Unit Adding holder ? That place far under and inside the machine... Who is that handy ?

Uint-shift... I rather use 15* 17 diecases.

!3 years ago I removed this attachment too. But than you need a plate, on the same spot, because otherwise the 0005- and the 0075-pistons will not get any air.

                             

Next to the attachment for Unit Adding (that is switched off) the plate covers the place wher I removed the Unit Shift Attachment.

I copied a metal plate with two plexy glass plates. glued to each other.

Three little channels conduct the air to the proper holes. It is easy to see which holes need to be connected.

With this plate, the basic Monotype code-system is restored:

        a) The correction wedges are replaced with the codes 0005 and 0075
        b) the galley-mechanism will be activated with the combination 0005-0075.
        c) Single justification can be used to correct the with of character and spaces.
        d) 5 unit white High Spaces can be used when the correction needed is 5 units or more

It might not be handy while typing on a keyboard, but with a computer-program it all goes very well.

[John Cornelisse]

Monotype made all kinds of attachments for the machine. Complicating the code, but I found that
the original coding system was very versatile.

Actually all those clever attachments, I do not use them at all.

No Unit Adding, because I do not have all the proper little wedges, and placing them in the
Unit Adding holder ? That place far under and inside the machine... Who is that handy ?

Uint-shift... I rather use 15* 17 diecases.

Quadding and centring. This is another attachment, I took off. Next to the papertower this blocks
the way the springbox need to go, when this needs to be removed from the machine...

!3 years ago I removed this attachment too. But than you need a plate, on the same spot, because
otherwise the code A, C and D will not be available, these pistons won't get air.

                             

I copied a metal plate with two plexy glass plates. glued to each other.

Three little channels conduct the air to the proper holes. It is easy to see which holes need to be connected.

With this plate, the basic Monotype code-system is restored:

        a) The correction wedges are replaced with the codes 0005 and 0075
        b) the galley-mechanism will be activated with the combination 0005-0075.
        c) Single justification can be used to correct the with of character and spaces.
        d) 5 unit white High Spaces can be used when the correction needed is 5 units or more

It might not be handy while typing on a keyboard, but with a computer-program it all goes very well.

[Keri Szafir]

As a matter of fact:
The manual switch valve box (plate 43 part a25D41D) on the rear side of the caster is for unit adding, and the little switch under the paper tower (plate 60, part 302E) is for unit shift.

The unit adding switch in the "IN" position re-routes 0075 and 0005; their traditional functions are replaced by NK and NJ (NKJ for double justification). It was introduced quite early; I haven't seen a post-WWII machine without it. The "OUT" position turns the unit adding attachment off and leaves 0075/0005 for justification purposes.

The unit shift valve has two positions: N (no unit shift) and S or dot (unit shift active).
There were at least two ways the valve box could be attached:
-screwed on right under the paper tower, integrated with a plate which also replaced a215E1 (plate 50) air connection block for quadding and centering. It's on your first machine, as well as on mine.
-attached with some distance to the paper tower, connected with copper tubes (probably the "retrofit" version for older machines, or earlier design) - it's on your second, older machine.
There is an additional relay valve box 303E (plate 60) activated by the D signal (if unit-shift is on) and reset by the springbox cam lever. After activation, it routes air from the supply to to the unit shift air pin. On reset, it vents the pin. Its purpose is to delay the lowering of the pin until the springbox moves backwards and the pin jaw tongs are open.
The air connection on the switch valve plate are as follows:
1. (top) - air supply, to the port closest to the caster,
2. (middle) - D signal - to the port farthest from the caster (activates the valve),
3. (bottom) - unit shift air pin - to the port in the middle.

What is more, there were 21 versions of the unit shift attachment, some of them meant for 15x17 diecases (only unit shifting), and others for 16x17 (additional row), like we have.
The descriptions on plate 60 note the ranges of caster serial numbers each of these versions were meant for. The numbers start at 22001 and end at 26952. I don't know what about earlier machines (maybe they were deprecated and meant for replacement by the Monotype Corporation?). Were the later caster equipped with unit-shift by standard, rather than retrofit? I don't know. My caster is #28539 and was factory-equipped with unit shift.
Actually, the only purpose I use this attachment for is accessing the 16th row. For Polish, you have 9 accents lowercase and the same amount uppercase. Multiply it by three (for roman, bold and italic) and you have whopping 54 additional matrices, making the extra row quite useful.

The stacked valve boxes next to this switch (plate 50 part 216D) are for quadding and centering, i.e. the signals AC and BC were using for locking the paper tower for 10 revolutions or indefinitely. I keep those valves on my machines, even though I have no use for them with computer control.