A true series is composed of similar filing units arranged in a consistent pattern within which each of the filing units has its proper place. The series has a beginning and it has an end, and everything between has a certain relationship. The pattern may

A true series is composed of similar filing units arranged in a consistent pattern within which each of the filing units has its proper place. The series has a beginning and it has an end, and everything between has a certain relationship. The pattern may be a simple one – alphabetical, numerical, or chronological – or a complex one, as, for example, annual reports arranged first by years, then by States, and then by counties within States. . . . There will occasionally be a series made up of only one file unit. . . . There will also be cases where no discernible pattern seems to exist for certain groupings of documents although a subject or transaction relationship is obvious. Often one really has just an accumulation of aggregation of documents relating to some matter because, apparently, the agency did not take the time to rationalize their arrangement. These accumulations can hardly be called 'series' in the strict sense of the word, but arbitrarily we treat them as such – just as we are somewhat arbitrary about what constitutes a record group.