[husker boxster]

Hello Road Hazard.

That string is used to keep the canvas tight on the top bows. Kind of old fashioned to use string, but that's what they do. That elastic band in the lower part of your pic is what keeps the top from slipping over the outer top bow. So both sides are untied? There's a panel that can be unsnapped with 2 velcro straps, giving you a better view inside the top. Otherwise an upholstery shop would probably know how to address it.

I don't have access to my Box (she's in storage) but I can swing by tomorrow and take some pics.

BTW...
It looks like you have a 987 from what I can see of your passenger doorcard. It's always good to mention what car you have (yr, base or S, etc) to give the membership an idea what your working on.