These data are physically unformatted. A number of error 

 checks are made before and after the gridded bathymetric data 

 are created. The gridded data then are placed on a random-access 

 storage device using a predetermined "look-up" table (list of 

 acronyms). At this point the data are ready to be accessed. 



At present, a bathymetric profile can be generated up to 

 8,000 nm long and crossing 30 MSQLOC areas. This limitation can 

 be increased if necessary. The accessing is initiated by 

 supplying the latitude and longitude of a beginning and end 

 point or the latitude and longitude of a beginning point with the 

 bearing and maximum range. Combinations of these accessing schemes 

 can also be used. 



The first step in retrieving a profile from the data bank 

 is to generate its great-circle path. At the same time each 

 MSQLOC area that the path crosses is identified and a search 

 table of MSQLOC areas is created. For each MSQLOC area the 

 search table contains the latitude and longitude of the first and 

 last point in that MSQLOC area, the forward-looking bearing at 

 both points, the accumulated range from zero for both points, 

 and the MSQLOC area number. In turn, each MSQLOC area is called 

 from the random-access storage device via the "look-up" table 

 and the profile for that block of data is generated. This partial 

 profile is then placed on a temporary magnetic tape. The next 

 MSQLOC area is called from the random-access storage device and 

 the cycle is repeated. At the end of profile generation the 

 temporary magnetic tape is rewound. The plotting program is 

 then called and the partial profiles are linked, punched on cards, 

 and plotted and/or written on magnetic tape. 



The accessing program is structured so that long profiles 

 generally are processed faster than numerous short profiles that 

 total the same mileage. The great-circle path generation requires 

 about 10 seconds for an 8,000-nm profile plus about 5 seconds 

 for each full MSQLOC area crossed for the interpolation. 



The only maintenance to be performed to the system is the 

 eventual updating of the gridded bathymetric data based on the 

 random-access storage device. This is easily accomplished by 

 recycling through the structuring phase of the system any MSQLOC 

 area that requires updating and then replacing that block on the 

 random-access storage device. 



A status report can be generated to check any or all MSQLOC 

 areas. This report includes the random-access device's compatible 

 data block size, the actual column and row sizes, the date the 

 data block was added to the random-access device, the MSQLOC 

 area number, the relative address, and the actual data, if required, 



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