Closure is often made as either a placket or as an extension of for example the front
Closure can be either buttons or zipper, and can be placed at different places at the garment
The extension is made to assure space for buttons and buttonholes. Extension measure is based upon the kind of garment and fabric and button. If you want to check you pattern, the extension is what is added from centre front.
It’s important to ion interlining into the extension. Normally it’s done to the back side of the extension. This to assure the fabric still got the same look as the rest of the garment. Sometimes you can easily see where interlining is placed because the fabric gets a little bit carbon like.
Different example for closure is a polo closure with or without placket, a front piece with buttons or zipper, a side seam with buttons, buttons at centre back, Velcro band at the shoulder seam ect. Ect.
The closure can be either visible, meaning the buttons are placed to be seen, or hidden where the buttons are covered behind some fabric.
