2.07 Summary

When setting the SI base units an important consideration was the ability to set the measurement standard for these units. This has lead to base units being chosen which are not necessarily simply the units of measurement of each of the base dimensions.

The need for convenient and practical units has lead to the definition of the mol a base SI unit which has no dimensions and the Candela which encompasses a range of dimensions.

The convention that has been adopted is that a base quantity is defined as a quantity measured by one of the seven base SI units (as opposed to choosing them to be the quantities corresponding to the five base dimensions)