Some Components have variable dimensions that must be specified in situ by the designer. Once a Component has been selected from the Specification, altering, say, the ANGLE may change its physical appearance.

Although many Component elements possess the ANGLE, HEIGHT or RADIUS attributes or use Design Parameters, it is the Catalogue that determines whether the value of these attributes will affect the physical Component. For example, changing the ANGLE attribute of a 90-degree fixed-angle elbow to 45 degrees will have no effect. In some cases, the variable value may be difficult to determine. For instance, a BEND in a pipe may possess an angle resulting from an oblique change in direction. In such instances, the DIRECTION command (described elsewhere) can be used to determine the ANGLE setting automatically.

The ANGLE, HEIGHT and RADIUS attributes can also be set before selection as a means of choosing between, say, 90-degree or 45-degree fixed-angle elbows.