Theaters of Opera and ballet, drama theatres are always more demanding of dress code, than a puppet, music, kids, and non-profit theatres. If the first mean suits and dresses, in the second sometimes you can even wear jeans. Pants and long sleeve shirt for men and blouse with skirt or pants for women will be a compromise for most views. No one in the theater shouldn't come in t-shirts, shirts, shorts and sandals - what the weather may be.
Steps to be taken before six o'clock, says the etiquette is less formal. This rule also applies to theatrefurther performances. For daytime and morning views as an acceptable form of clothing are dresses of all colors knee length or below for women and trousers with neutral shirt colors for men. A woman can afford to wear up to six nights any jewelry, but we all know that a diamond necklace is unlikely to put on performance theatre-buff.
After six in the evening it's time of formal events that require formal suits and long dresses from the women. Nowadays in most theatres do not need as before, to wear an evening dress, but a suit with a few sophisticated accessories, or classic little black dress with pearls or diamonds would be more than appropriate. Needless to say, this form of clothing require heels and a small purse to match. From men expect dark suits with light shirts and a solid tie.
Theater, particularly Opera and ballet, premieres, benefit performances of the great artists, jubilee performances - an occasion for women to dress up in evening dress, and the man to demonstrate how he is irresistible in a tuxedo.