At least 80% iceberg lettuce. Iceberg lettuce is crucial to the structure of the Taco Salad.
Without protein, it's just a salad. Ground beef is classic, but there are many options.
Without crunch, it's just a salad with protein. Tortilla chips define the standard for taco salad crunch, but there are other choices available.
Thousand Island? Ranch? Both classics, but there are other allowable variations to consider.
Cheese rules! There are also cheese rules! The first rule of cheese is that it is optional, to allow for dietary considerations.