- Period (currency): Transient. Although siegeworks appear in England in the 12th century they do so in the form of one of a pair of mottes, which are considered as a separate class of monument; other siege works were used, in the form of emplacements for ballistic weapons, as the only known surviving example at Berkhampstead shows; these are not considered to be fieldworks as the use of fire artillery was not involved, and they are excluded from this description. The extensive use of fieldworks appears after the development of artillery and the tradition of construction on the Continent extends over 200 to 300 years or more. In England the tradition extended for little more than 20 or 30 years, throughout and for a short period after the Civil Wars of 1642 to 1652.
- Rarity: Rare. The number thought to exist is 148; this may change as investigations continue, but any change is unlikely to be significant.
- Diversity (form): Very high. There are 6 main types, some with further variations in form, as well as other significant factors,listed in the provisional classification noted above. No chronological or regional variations have been noted.
- Period (representativity): Medium. There are many contemporary classes of monument, of which fieldworks is one of the few devoted to defence at this period.
Assigning scores to these criteria following the system set out in the Monument Evaluation Manual, fieldworks yield a Class Importance Value of 30. This is nearly halfway up the range of possible values, (max. 64), reflecting the wide diversity and rarity of this class of monument.