FIELDS M and N 



Columns 45 and 46; 



47 and 48 



only with a single dose level. However, it is possible that as a result of several determinations using 

 a number of organisms, a threshold dose or a maximum tolerated dose may be expressed as a range of 

 doses, a given percentage of the organisms having the threshold or tolerance at one level, another 

 percentage having the threshold or tolerance at a slightly different level, etc. In the latter case, 

 Fields M or N should be coded to include both extremities of this range of threshold doses or maximum 

 tolerated doses (double coding if necessary) and the Grid should be used to derive a Field Y rating as 

 described in the specific directions and explanations for Fields W, X, and Y, Division 14 (paragraph 8) 

 and Division 15 (paragraph 8). 



17. Further consideration of double coding in Fields M and N; relations to double coding in other 

 fields 



The construction of a single line for several tests (when there is variation in the test dosage, 

 yet the test results are so similar that they can all be coded by a single symbol in Field Y) is described 

 in the preceding divisions. This coding procedure, which calls for double coding in Fields M and N 

 with that single code symbol in Field Y, is in general the same procedure as used when duration of 

 administration (Field P) or duration of action (Field U) is the test variation rather than the dosage level. 

 In such a case, Field P or U is double coded with a single evaluation symbol in Field Y and all entries 

 are punched on the same IBM card. 



Occasionally, test data are encountered in which, in a series of tests, the variation in the 

 tests is not just dosage size or just duration of administration, but variation in dosage size as well 

 as duration of administration or duration of action, and the evaluation for two or more of these tests 

 is expressed by a single symbol in Field Y. Since coders frequently attempt to double code the dosage 

 fields and another field in the same line (Field P, U, or V, e. g. ) and err in doing so, it will be dis- 

 cussed here briefly. 



Observe first that when only one field is double coded, the subsequent interpretation of the 

 line is uncomplicated, as follows: The test evaluation given in Field Y was the test result regardless 

 of whether the larger or smaller of the two values coded in the double- coded field was used in the test 

 method. (E. g. , if Field N is double coded and Field Y is coded to indicate moderate activity [Symbol 5], 

 that degree of activity resulted from any dose between the highest and lowest indicated by the coding 

 in Field N. ) 



However, when two variables occur in a test method and when several of the tests give results 

 that can be indicated by a single symbol in Field Y, if two fields are double coded to record the two 

 variables, coding must permit the subsequent interpretation as direct and uncomplicated as in the 

 example of the above paragraph. It is with this situation that the coder must exercise caution. The 

 regulation which must be followed when two or more fields are double coded is explained diagram- 

 matically below. 



In considering the double coding of more than one field in a single line, the coder must 

 deliberate upon the inter-relations of the entries for those fields to be double coded, as indicated by 

 the statements of the diagram. (It is possible to write in code that 10-mg doses given hourly for 4 

 days will give the same test results [or at least test results coded by the same symbol in Field Y] as 

 100-mg doses hourly for 12 hours; it is not possible to punch this and retrieve it by the IBM machines 

 used by CBCC and retain the strict association between each dose and its own period of administration. 

 The reasons for this procedure will be appreciated only through understanding that the IBM machine 

 methods used by the CBCC will not allow any other procedure. 



93 



