[rotorwrench]

They are referred to as listings. Some are looped for a wire to go through and some are just a strip of fabric to tack or staple to a wood bow or tack strip. Sometimes they are all looped to make them stronger and easier to assemble when sewing the panel up. They also give a person a straight line reference of distance between the top edge of the listing and where the headliner will set away from the bow or tack strip. A person can mark a line on the wood bows if they need to.

Each one creates a seam line in the head liner so the distance between bows is relevant to the way they are made.

When applying adhesive, take care to try to apply it where it can't be easily seen when bedding it down. Some adhesives can soak through the fabric depending on type of fabric and it can be seen if a person isn't careful.

There used to be some good youtube videos for headliner installation but I've not looked at that stuff for a long time. The key is starting on the front to rear center line of the panel and matching it to the center line of the roof. Chalk can be used to mark stuff since it can be removed. Some cars are better to start from the rear but many start from the front. It largely depends on the way the car is designed.