A regular aggregate field system is two or more enclosed units of land set aside for cultivation and/or pasture, defined by boundaries laid out in a consistent manner, along two axes set at right angles to one another. In a strict sense they conform to a coaxial principle, but can always be distinguished from coaxial field systems by the area they cover; never more than 100 ha. The only exception to this upper size limit will occur in systems which comprise several blocks of adjoining fields which each conform to a different alignment, creating the impression that they developed through a process of accretion.
Unlike the larger coaxial systems, conformity to a single axis of orientation over a wide area was not a major concern in the construction of field boundaries. This is amply illustrated by the common location of regular aggregate fields on the periphery of coaxial systems, where they follow an entirely different alignment from the larger complexes.
The size of individual fields can show a considerable range of variation which generally falls between 0.1ha and 3.2ha. A similar diversity exists in relation to field shape which can be square, rectangular, long and narrow, triangular or polygonal.
Field boundaries are formed by a variety of earthworks which include "drystone tumble" walls or reaves, orthostats, earth and rubble banks, pit alignments, ditches and lynchets. These will either follow a straight or sinuous course and may include a number of kinks and similar irregularities. Boundaries are linked to one another in a variety of ways which produce continuous, staggered, gang, side-step, or T-junctions. Component features common to the majority of regular aggregate field systems also comprise entrances and trackways.
Confusion might occur in attempting to distinguish between rectilinear settlement enclosures and some of the smaller field units. Although similar in ground plan and size, enclosure boundaries ought to be larger in scale. The ditches are generally wider and deeper and the banks/walls broader and taller, than the boundaries marking the edges of field units.