Many guests invited to a wedding often are as concerned as the bride and her attendants with what they will wear.

There are a couple of golden rules to remember. First, don’t wear white — it upstages the bride. And second, don’t wear black — you’re not going to a funeral. For many women, this meant having the reliable pastel dress and matching pumps in the closet, patiently waiting to be worn for the wedding du jour.

But what to do when it comes to a formal affair? Today, even though dress codes have become somewhat relaxed, there are still some guidelines that savvy brides and grooms might consider including on their invitations if their wedding is a formal event. Guests are usually grateful for this considerate gesture, especially in an age where often “anything goes.”

Here’s a helpful lexicon from “Town & Country Elegant Weddings” (Hearts Books).

Black Tie: This means that women must wear evening dresses (short or long) and men should wear traditional tuxedos.

“Pantsuits are not proper,” says etiquette expert Letitia Baldrige, the former White House social secretary to Jacqueline Kennedy, advice columnist and author of several books, including “Letitia Baldrige’s New Manners for New Times: A Complete Guide to Etiquette.” Nor is any other kind of suit acceptable as it would be out of place.

Black Tie, Long Gown: This is not a common edict, but found occasionally. Some couples find that this gives guests more clarification when the occasion is very dressy.

Joan Rivers, for example, used this specific dress code on the invitations to her daughter Melissa’s fancy New York wedding because she felt dress was important to the overall effect of the event.

Black Tie Optional: A bewildering dress directive for many guests, this option is considered by many etiquette experts to be very confusing.

“It’s the worst phrase in the English language,” says Baldrige. Dallas socialite Lynn Wyatt “looks in horror” at an invitation that uses this phrase. When it does appear, she says she never dresses up. As do most people who take the word optional to mean they don’t have to wear black tie. Those few who do dress up often feel out of place, making for a very mixed-up (and mixed-dress) crowd.

Creative Tie: Another distressing dress code, according to Baldrige. “An affair should either be black tie or not,” she says. “If it is not, you need say nothing at all.”

However, fashion designer John Anthony believes that an invitation stating creative tie signifies that the hosts want the guests to be more thoughtful and lavish in considering their attire. It might mean a patterned cummerbund for the man and a frock that’s something other than the usual little black dress for a woman.