The four criteria for assessing class importance apply to linear boundaries as follows:
- Period (currency): Long-lived. Linear boundaries were constructed and maintained for a period of more than 1000 years beginning towards the end of the earlier Bronze Age; established systems appear to have been maintained and modified until sometime during the Iron Age.
- Rarity: Common. Linear boundaries extend across considerable tracts of countryside. Estimates can be based on a 450 square kilometre intensive survey which revealed that the total length of ditches amounted to more than 224km. In Wessex alone systems of linear earthworks cover a total area of over 4000 square kilometres.
- Diversity (form): Medium. Three main types of linear earthworks have been identified.
- Period (representativity): High. Linear boundaries represent one a restricted number of monument classes belonging to the Bronze Age and Iron Age. During this period they seem to have occupied a central position in the division of the landscape into large scale units.
Assigning scores to these criteria following the system set out in the Monument Evaluation Manual, Linear boundaries yield a Class Importance Value of 33 which lies just over half way up the range of possible values (max. = 64), reflecting the long currency of use and the representativity of the class. Examples representing both types and of varying date should be included in the sample of nationally important sites.