The four criteria for assessing class importance apply to coaxial field systems as follows:
- Period (currency): Long-lived. The tradition of constructing and using coaxial fields systems spans a period of 1600 years or more. The major phase of construction was, however, in the later part of the second millennium BC. The duration of individual systems is poorly documented, although in some areas they appear to have been maintained for nearly a thousand years. On Dartmoor, for example, the earliest dates indicate the construction of reaves began around 1700 BC, continued throughout the second millennium and were maintained well into the first millennium. Other systems, such as those aligned on Roman roads, may have had a more restricted currency.
- Rarity: Very rare.Although the exact number of recorded sites is not known it is probably between 40 and 50 separate systems, altogether covering several hundred square kilometresrecorded. These figures are based upon a limited number of regions where the data available on aerial photographs have been analysed in detail.
- Diversity (types): Low. Two types of coaxial field system can be defined. This slightly masks the overall range of variation. The degree of infilling within systems exhibits a continual increase in density between Types 1 and 2, while there is some indication that the average size of fields may vary between regions and between systems. Several forms of boundary have been identified, all of which can occur in a variety of combinations.
- Period (representativity): High. As a direct result of their long-lived currency any assessment of representativity must be an average. The overall range is "very-high" for examples which are early in the tradition and "medium" for those towards the later end of their construction and use.
Assigning scores to these criteria following the system set out in the Monument Evaluation Manual, coaxial field systems yield a Class Importance Value of 42. This lies about two-thirds of the way up the range of possible values (max.= 64). Examples representing the full range of types, and variations in size and orientation, must also be included in the sample of nationally important examples, as too examples from all the regions in which coaxial field systems occur.