Methods of constructing classification scheme

By Adimu Nihuka Jr
For library students and others who learn library studies. In this decade there are unique methods of constructing classification scheme, these methods are discussed below:-

There are three broad methods, these are:-
1)Hierarchical scheme
2)Enumerative scheme
3)Facet scheme (Analytical synthetic)

Hierarchical scheme
This method follow the classical theory of categories by Aristotle, creating categories from general to specific. For instance; Case of DDC all items are arranged hierarchical. Example; DDC starts with 10 main classes, each class is divided into 100 divisions, each division is divided into 1000 sections, each section is further divided into ten thousands subdivisions and soon.

Enumerative scheme
Traditional library classification schemes it tends to list all subjects terms either simple or complex and their subdivisions and provide read mode symbols for them. Example; DDC is considered the most full enumerative.

Faceted scheme (analytico- synthesis)
Its a modern classification scheme. It do not attempt to list or enumerate compound subjects. Also facets are homogeneous group.
The scheme is called analytico- synthesis because it break down knowledge into single subject concept then combine them to represent total subject content of a document.
Foe instance;  the book entitled "Economic crisis in the European Union during the 20th century".
Also you can analyse the above subject heading using PMEST formulae as adopted by Ranganathan the classifier. The above can be analyzed by citation order by using PMEST as follow:-
Economic
Crisis
European Union
20th century

PMEST is abbreviation of;
p= Personality
M= Matter
E= Energy
S= Space
T= Time

Also formula above is adopted by the classier called Ranganathan which means:-
Personality stands for the subject of the documents
Matter stands for the aspect of the object
Energy stands for the process, operation, technique
Space stands for location
Time stands for period which action takes place

Note:
>The first digit in each three digits represents main class
Example 500 Underlined is a first digit
>The second digit in each three digits represents division
Example; 510 the underline digit is division
The third digit in each three digits represents the section.
>Example; 512 the underlined digit is section.