Al'TOMA'PIC TOT.L SWITCH! \(; SYSTEMS 



877 



Fig. 



Punched card. 



later. For certain calls such as calls to operators only four or five digits 

 are needed. These are treated as six-digit calls by having the sender 

 suppl}' the extra one or two digits to fill the complement. The NCA hole 

 enlarged means "no come again", that is, three digits are sufficient, and 

 translation will proceed. The other holes enlarged mean respectively 

 "come again when 3'ou have four, five or six digits", and no fiu'ther 

 translation is done until the sender comes back a second time, prob- 

 ably to a different decoder, with an indication that it has the required 

 number of digits. 



The OGT appearance holes are used in a two-train office to tell 

 which train the outgoing tmnk appears on and enable the decoder to 

 select a marker in the proper group. 



The remaining holes on the top lines are for controlling operation of 

 traffic meters. 



The translator box number holes in the second line arc punched on the 

 area code cards to indicate which machine contains the indi^•idual cards 

 for the called area when six-digit translation is required. 



The INDl hole in the second line and the IND2 hole in the fourth 

 line are index holes and are never enlarged. Any card that drops will 

 always cut off the light through those channels. This serves as an indica- 

 tion that a card has actually dropped and that the phototransistors 

 a.ssociated with the other holes should be prepared for action. The index 

 holes also aid in trouble detection and in proper disposition of calls 

 where cards are deliberately omitted or wliere operators have dialed 

 a blank code in error. 



