A perforator is a closed shape which acts as a cutting element to create openings in forms to enable the insertion of compound cells and parametric frames. Perforators are construction class elements that are normally turned off and hence they are not normally visible.

When multiple perforators exist, the construction order of openings depends on the perforators. For example, the first perforator creates an opening in the first identified form, the second perforator creates an opening in the second identified form and so on. Where the number of perforators is exceeded by the number of forms, the last perforator is used in all subsequent forms.

When compound cells and parametric frames are placed and perforators are not used to create openings in the forms, the form will continue to pass through the placed object and obscure it from view when the model is rendered. In addition, quantity reports will not include required openings.