Also, many exponents of filing knowledge have saidthat their file is a "fool-proof" one. I believe that youquestion this statement, as the only way to have afile as near perfect as possible, is to have safe andsane ideas and put them into practice; that is whythe Alphabetic file is the 95% file.
Alphabetic filing accounts for 95% of filing systems according to Butters.
The reason for this beingin the Complex classification is, as one will tell youwho has operated a Subject File, because a great dealof care must be exercised in not only laying out theproper plan, but working in and cooperating withthose who send matter to be filed, and are constantlyasking for it. The file clerk may think it goes in oneplace, but unless it is carefully marked as to whereit should be filed and then remembered, and possiblyagain classified by card, it is many times found a dif-ficult matter to handle.
The next Complex method in order, is the Numeric,which may be divided into three classes, straight num-eric, duplex and decimal. It is safe to say that withthe straight Alphabetic or Geographic, ninety-five per-cent of the cases where an Index is used will be moreefficiently handled by the use of either one of theseMethods, than by the Numeric. However, there aresome cases where there is a great deal of cross refer-ence, thus making the use of the Numeric methodmore advantageous.
This is likely the reason why most commonplacers using index card systems use alphabetic set ups by subject rather than Niklas Luhmann's duplex numeric variation.
The material filedcan be arranged as the cards would be,so as to bring together all the paperson a given subject.
is essential in subject work becausesome subjects are closely related andyet not sufficiently so to be filed to-gether.
The use of the cross reference sheet
A portion of the reason why Luhmann chose a duplex numeric filing system for his zettelkasten.
The object of any system is speedin service, and to obtain this, in sub-ject work, all correspondence on agiven subject must be filed together,regardless of who wrote it or at whattime it was written, so that the historyof everything that has taken place onone subject may be found in one place.
UBJECT filing is a branch of filingwhich is not much used in thebusiness world but which deservesas much attention as any other. It ismore complicated than other systemsand an adaptation has to be workedout for each , business to which it isapplied, but after the classification hasonce been made, it will prove to be foreconomy and increased efficiency.
Wigent, William David, Burton David William Housel, and Edward Harry Gilman. Modern Filing and How to File: A Textbook on Office System. Rochester, N.Y.: Yawman & Erbe Mfg. Co., 1916. http://archive.org/details/modernfilingate02compgoog.