No work in a specialized field would be complete without its own occult paraphernalia, and the curious reader may desire and explanation of the strange wizardry behind the document classification symbols. The documents in the American series are classified under the cryptic categories of "L," "R," "PS," "EC," "ECH," "ECR," and "C." The letter "L" was used as an abbreviation for "London," and designates those documents either obtained from American and British sources in London or processed in the London Office of the OCC, under the direction of Col. Murray C. Bernays and Col. Leonard Wheeler. Jr. The letter "R" stands for "Rothschild," and indicates the documents obtained through the screening activities of Lt. Walter Rothschild of the London branch of OSS. The origins of the "PS" symbol are more mysterious, but the letters are an abbreviation of the amalgam, "Paris-Storey." The "PS" symbol, accordingly, denotes those documents which, although obtained in Germany, were processed by Col. Storey's division of the OCC in Paris, as well as those documents later processed by the same division after headquarters were established in Nurnberg. The "EC" symbol stands for "Economic Case" and designates those documents which were obtained and processed by the Economic Section of OCC under Mr. Francis M. Shea, with field headquarters at Frankfurt. The "ECH" variant denotes those which were screened at Heidelberg. The letter "C," which is an abbreviation for "Crimes," indicates a collection of German Navy documents which were jointly processed by British and American teams, with Lt. Comdr. John Bracken representing the OCC.

The British documents hence include some in the joint Anglo-American "C" series. The remainder of the British documents are marked with the symbols "TC," "UK," "D," and "M." The symbol "TC" is an abbreviation of "Treaty Committee" and signifies the documents selected by a Foreign Office Committee which assisted the British prosecution. "UK" is the abbreviation for "United Kingdom" and indicates documents collected from another source. No especial significance lurks in the letters "D," and "M," which were apparently the result of accident, possibly caprice, rather than design. As a matter of record, however, "M" stands for the first name of the British assistant prosecutor. Finally, "D" is merely an humble filing reference, which may have had some obscure connection with the word "document."

The reader will note that there are numerous and often lengthy gaps in the numbering of documents within a given series, and the documents are not numbered in any apparent order. This anomaly is accounted for by several different factors. As the documents avalanched into the OCC offices they were catalogued and numbered in the order received without examination. Upon subsequent analysis it was frequently found that an earlier document was superseded in quality by a later acquisition, and the earlier one was accordingly omitted. Others were withdrawn because of lack of proof of their authenticity. Occasionally it was discovered that two copies of the same document had been received from different sources, and one of them was accordingly stricken from the list. In other cases blocks of numbers were assigned to field collecting teams, which failed to exhaust all the numbers allotted. In all these cases no change was made in the original numbers because of the delay and confusion which would accompany renumbering. Nor has renumbering been attempted in this publication, and the original gaps remain. This is because the documents introduced into evidence carried their originally assigned numbers, and students of the trial who use these volumes in conjunction with the official record will therefore be able to refer rapidly from citations in the record of the proceedings to the text of the documents cited.