1313.4 Use of Broken Lines in Drawings
The applicant should use broken lines to depict structures that are not part of the claimed design. The broken lines should not intrude upon or cross the depiction of the claimed design, nor should the broken lines be of a heavier weight than the lines that depict the claimed design.
If a broken line must intrude or cross the depiction of the claimed design to depict the environmental structure, that drawing must be submitted in addition to one that clearly shows the claimed design without the intrusion of broken lines. 37 C.F.R. § 212.3 (E) (3)(ii)-(iii).