Two different classification schemes have been used to define the structure of this family.

A synthesis of the various classification schemes is provided in the table below.

The classification scheme is based on the way consumers purchase.

However, from 2002 a new classification scheme has been adopted.

However, it is important to remember that "his work represents a major step along the way to the modern classification scheme."

Specific classification schemes for particular subjects or types of materials.

One example of a classification scheme for data elements is a representation term.

There have been a number of other general classification schemes devised over the past 100 years.

In some senses these could also be regarded as special classification schemes.

However, this classification scheme has not generally been followed by other researchers.