The word religion seemed to mean the Christian religion only. Further it had an American bias. Even though European history goes back further in time than American history, the latter had twice as many pages in the classification. The index which was thought to be very helpful actually caused inconsistent cataloging. This can not be blamed on the index but rather on the shortcomings of librarians.
Librarians tend to suffer from classification by attraction.
This causes them to ignore the schedules and largely base their classification decisions on entries from the index on which their eye happens to fall. This in combination with the tendency to pick a specific heading instead of the correct but non-specific heading caused related items not to be grouped together. Improvements to the different editions of the Classification Until the fourteenth edition, the structure of the Classification mainly stayed the same with only the amount of detail increasing. In the fifteenth edition, an attempt was made to get the scheme up to date. Standard spelling and modern terminology were also adopted in this edition.