Each simage is composed of a collection of primitive visual elements, or privels. Table 1 shows a list of some privels.
| Table 1 | |||||
| Privel name | attributes | ||||
| generic-visual-element | location, size | ||||
| line | start-point, end-point | ||||
| thickness, location | |||||
| circle | location, size | ||||
| box | location, height, width, orientation | ||||
Objects in the domain, like the fortress, are associated with a privel type. Each privel type has attributes associated with it. As shown in Table 1, lines have a start-point, an end-point, a location and a thickness. These attributes are not strongly-typed. For example, the end-point of a line could be a location such as the ``center'' of the image or some component of the image, like the fortress.