creo3 Drawing Setup option documentation for: show_offset_section_seams 
show_offset_section_seams
Controls the display of the seam that exists between segments of an offset section, outside the total unfold views.
Default and Available Setting:
angled_only* - Seam is shown for segments at angles other than 90
degrees.
all
- Seam is shown for all segments including perpendicular segments.
none - Seam is not shown for any segment.