They were either plain or quatre-foiled.
"English Villages" by P. H. Ditchfield
The shield above is pierced with a bold quatre-foil.
"Scottish Cathedrals and Abbeys" by Dugald Butler and Herbert Story
The surface is enriched with three bands of quatre-foiled work, and the angles are decorated throughout with ball-flower ornament.
"Ecclesiastical Curiosities" by Various