1048 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER, 1953 



as may be required through step-by-step toll trains. Facilities are pro- 

 vided for the outpulsing of one, two or three digits as may be required. 



The VARIABLE SPILL CONTROL holes On the sixth line inform the 

 sender when to pulse forward all digits as received, or to omit sending 

 the first three or six code digits. 



The remaining holes on the card define the location on the switching 

 frames having the desired outgoing trunk appearances. The notches 

 around the outer edges of the card are for proper positioning of the card 

 in the stack and for card removal purposes as will be discussed later. 



CARD OUTPUT DETECTION 



The enlargement of the holes in the face of the card to obtain the 

 translation output as previously stated is recognized by means of modu- 

 lated light beams falling on phototransistor detectors. With all of the 



Fiij. 6 — Normal (above) and dropped card views as seen from the photo- 

 transistor side. 



