There are three types of vinegar mix for dressing, Nihaizu , Sanbaizu , Amasu . Add different ingriedents to these basic vinegar mixes.
Variations are available.
Basically, vinegar and soy sauce mixed. Amasu Vinegar and sugar. More sweet than sour. Add Dashi to make flavor mild. Use less soysauce and add a little salt to taste lightens color of ingredients.