A quick note regarding placing ink, felt tip pen markings on the underside of your vinyl. DONT DO IT!
Sometimes it may seem unavoidable, especially if you only have access to the underside of the sheet while unfolding it.

Underside of Sheet Vinyl
Top side of Sheet Vinyl
Use the masking tape to write or mark on any vinyl surface. sometinme you canget away with a small pencil mark. NEVER with a FELT TIP

A quick note regarding placing ink, felt tip pen markings on the underside of your vinyl.
DONT DO IT!
Sometimes it may seem unavoidable, especially if you only have access to the underside of the sheet while unfolding it.