Trian Aspect

Items drawn in 3D, or in 3/4 profile, or so that there is visible depth to the item. Normal heraldic depiction is very "flat" and two-dimensional, rather than a more naturalistic, or three-dimensional depiction. Therefore, other than a few charges which need this depth to be identifiable, such as dice, wedges of cheese, and tambourines, charges in trian aspect are not registrable.

http://heraldry.sca.org/coagloss.html