The radius defines the circumradius of the n-sided polygon on the end caps.
If a major and minor radius are used, the end caps are bounded by a circum-ellipse instead of a circumcircle.
The number of sides of a prism must be greater than or equal to three. A prism may also be created using the pyramid command with all radii set to the same value.
If the Extended option is specified with Bounding Box, the result is a brick that is extended from a "tight" brick by the input percentage or absolute value.
If a bounding box specification is used in conjunction with any of the other parameters (X, Y or Z), the parameters specified override the bounding box results for that or those dimensions.
