THROWDOWN MACHINE FOR TRAFFIC STUDIES 353 



is determined by switch and frame numbers. There are ten sets of Une 

 links per Une Hnk frame and a maximum of twenty frames. The identi- 

 fication of each set is a three digit number made up as follows: 



SW-LLF 



where SW — switch number (0-9) 



LLF— frame number (00-19) 

 This provides for a total of 200 line Hnk sets or cards. 



The number of the line link set is incorporated in the line identification 

 number so that from the latter can be determined immediately the 

 particular line links available to the line. Note on Fig. 24 that line 803-24 

 must use the LL803 set of Hnks (card shown on Figs. 25 and 26) for any 

 connection. 



There are twenty sets of trunk links per trunk hnk frame (ten left 

 and ten right sets) and a maximum of ten frames. The identification is 

 a two digit number plus a left or right indication. The number is com- 

 posed as follows : 



TLF— SW 



where TLF — frame number (0-9) 

 SW — switch number (0-9) 

 and the left or right indication is, for convenience, one of two colors. 

 This provides for a total of 200 trunk link sets or cards, 100 of each color. 

 The link identification is included in each trunk number. Thus, on Fig. 

 24, trunks 21-49 must use trunk link set TL 49, either left or right. 



The number and disposition of junctors are determined by the layout 

 of line link and trunk link frames. In a 20 line hnk-10 trunk link frame 

 office, there is one set of junctors between each pair of frames. For 

 fewer frames there are more sets between frames to a maximum of five 

 for a four-line link, two-trunk hnk frame office. The junctor sets or 

 cards are identified by the two frame numbers involved, as 



LLF— TLF 



where LLF— Line Link Frame No. (00-19) 

 TLF— Trunk Link Frame No. (0-9) 

 If more than one set of junctors interconnect two frames, letters A to 

 E are added to the base number. For a particular line and trunk, the 

 junctor number is derived from a combination of the line and trunk 

 numbers. For example, the essential parts of line number 803-24 and 



