FIELD A 

 Column 9 



solid (the state prior to introduction into the water, saline, etc. ) would not serve any useful purpose 

 in this situation, this field should be coded with the state of the compound in the host water or 

 nutrient (i. e. , the state as applied to the test organism) rather than with the state when added to those 

 hosts. 



6. Coding in Field A when the test compound has been applied to a surface as a residue 



Occasionally, a test compound is introduced onto a surface (or in a cloth, filter paper, etc. ) 

 in an organic solvent, for example, which is subsequently allowed to evaporate, leaving the test 

 compound as a residue. (I) If the technique dictates that the test organism is then exposed to the 

 residue, Field A is correctly coded with the state when applied to the surface, according to Division 4 

 above. (II) However, if this treated surface (e. g. , an aquarium inner surface, microscope depression 

 slide, Petri dish, a filter paper disc, etc. ) is then immersed in water, for a test with aquatic organisms, 

 "water" is to be coded in Field J, nothing need be coded in Field C, and Field A is to be coded only if 

 it is known or stated that the compound is completely soluble in water; otherwise, Field A will be left 

 uncoded. 



7. Coding in Field A when the test compound is a gas 



If the test compound is administered as a gas and its concentration is expressed by the author 

 only in terms of this gas (e. g. , per cent test gas in N, O z , or air) which is subsequently streamed 

 through (1) a bath or perfusate of an organ, tissue, or immersed organism, or (2) a suspending medium 

 of a tissue macerate or an enzyme-containing secretion (e. g. , milk), the concentration of the test 

 compound in the gas will be coded in Field M. Therefore, in this case, Field A must be coded with 

 "gas", Symbol 1, and Field C need not be coded, since the suspending solvent is implied in coding 

 the preparation as a homogenate (Field G) or secretion (Field I) or in coding the diluent of the homog- 

 enate (Field J). Note, however, that if the author should actually have determined the dissolved con- 

 centration of the test compound, coding in Fields M and C should be based on that concentration and 

 solvent and Field A should be coded with "solution", Symbol 4. 



8. Indication of information on correlation between chemical structure and biological activity 



The Symbol is used (either alone or with one of the symbols for physical state) to indicate 

 that the article contains information on correlation of chemical structure and biological response. 

 The information may deal only with the compound under test or with a series of which the test compound 

 is a part. When an article contains information about the relationship of chemical structure to a certain 

 biological effect, Symbol should be coded in Field A in each code line which describes that effect 

 (Field T) for all the compounds whose chemical structure is discussed. Symbol should not be coded 

 in lines for other actions which happen to be in the article but for which the relationship to chemical 

 structure is not discussed. 



When using Symbol 0, it is necessary to give some idea, in the language portion of the code 

 line, of the information contained in the article. Do not write merely, "structure-activity"; write 

 (e. g. ), "activity of q, (3, y isomers studied" or "effect of methyl, propyl groups studied". 



9. The nature of items 2, B, K, 3, and C 



Note that Symbols 2, B, K, 3, and C refer to undiluted compounds. 



10. Symbols available for additional items of Field A 



The following symbols have not been used and are available for items of Field A: 8, 9, H, I, 

 J, L, P, 0, and R. Symbols S through Z are not available, because the IBM zone punch has been used 

 as a special symbol. If the available symbols are used to conform to the established organization of 

 the field, Symbol J should be used for a gaseous state as are Symbols 1 and A; Symbol L should be used 

 for a state of an undiluted solid compound as are Symbols 3 and C; and Symbol P should be used for a 

 suspension-in-a-solid state as are Symbols 7 and G. The six remaining symbols can form two new 

 groups: (1) 8, H, and Q and (2) 9, I, and R. 



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