Before training as a costumer, the only swing tacks I ever saw were used as belt carriers on women's dresses. I thought the wonderful little stitches looked just like a crochet chain; uniform, even and very strong. Besides belt carriers, swing tacks are used to keep two layers of fabric connected, but allows for some movement. For example, swing tacks are often used on dance costumes to keep the layers controlled, despite all the movement. Period costumes may incorporate the swing tack to keep jacket lapels, front aprons or sashes from flapping around and distracting the audience. A snap closure may be stitched to the ends a swing tack to work as a bra strap carrier on the inside of a costume. Use a heavy double thread for swing tacks; and wax if necessary. Practise making a swing tack so you are ready to repair or make one on the next wardrobe call.
The book The Costumer's Notebook is a 295 page comprehensive handbook for Costumers for stage and film including a full Glossary of stage and film industry terms. Sections include methods and tricks for laundry, dyeing, breakdown, Dresser guidelines and protocols for Stage or Film and various size charts for men and women from shoes to gloves. Other Sections include diagrams showing How to Iron A Shirt, How to Tie a Tie and How to Tie a Bow Tie. Costume fittings, costume lay out and costume storage are also discussed.