The relationship between structuring programs is given in 

 a flow diagram in figure 7. The main processing programs are 

 SYNTRACK, SYNCARD, SYNCHEX, SYNGRID, SYNC0N2R, and SYNBLOCK (list 

 of acronyms). One additional program that is unique to this 

 particular system is the digitizer scaling program (CALMA 485) 

 which scales on a Mercator chart the latitude, longitude, and 

 depth for each contour intersection along the track. The output 

 from this program is a binary magnetic tape of scaled values. 

 Any digitizer and/or digitizer processor program can be used as 

 long as it generates the same program elements regardless of 

 output mode. 



The MSQLOC area to be digitized is mounted and leveled on 

 the digitizer table (fig. 7) . Starting in the lower left corner 

 each track is scanned for data points from left to right and 

 from bottom to top. The tracks are scanned an additional 5 

 minutes on each end to permit interpolation rather than extra- 

 polation on end points in the gridding program. The MSQLOC 

 identification and operator name are entered as a header informa- 

 tion group before the data scanning is begun. The binary coded 

 decimal (BCD) magnetic tape generated by the digitizer is 

 processed by the CALMA 485 processor program to produce a binary 

 magnetic tape of scaled latitude, longitude, and depth data. The 

 binary tape is processed by SYNTRACK which: 



• breaks up the data string into tracks, 



• checks for missing data points, 



• checks for operator errors, 



• reformats the data to card image, and 



• punches out a header card, track card, data cards 



(one point per card) , and a blank card. 



An illustration of this deck structure is given in figure 8. After 

 errors have been corrected, the card deck generated by SYNTRACK is 

 run through the SYNCARD program. This program checks to insure 

 that the longitudes of contour intersections are not repeated, but 

 either increase or decrease depending upon quadrant. In addition, 

 this program tests the depth value to determine if it is within 

 about plus or minus two times the contour interval. In regions 

 of rapid depth change contours may be skipped if they are evenly 

 spaced. All errors are flagged for correction. 



After all corrections have been made, the card deck is run 

 through the track plotting program (SYNCHEX) . This program plots 

 the tracks as they were digitized and annotates each contour 

 intersection on the synthetic track line with cross ticks. This plot 



12 



