My father used to be fond of sending food back. Most often, it was the steak ordered medium-rare that arrived bloody or gray, but never just right. The family breathed easier when he got roast chicken.

Like every other diner, he had in his mind what medium-rare meant. As did every cook, who in those days would plant a little wooden stake that said "medium-rare" in the steak before sending it out. Customer and cook usually didn't share their visions until it was too late.

Nowadays, many people have taken to ordering their meat by color rather than by term. And many restaurants train their servers to explain how the establishment sees rare, medium, and so on.

Because degrees of doneness are open to interpretation. Local restaurants seem to agree on what's medium, but rare and well-done vary a lot. (See 'Degrees of Doneness' chart).

The gamut from blue to black does have signposts.

The Outback Steakhouse in Cupertino serves 700 steaks a night, says owner Bill Sullivan. He doesn't want a lot of them bouncing back to the kitchen. To avoid that, Sullivan has the servers repeat orders back to the customers. Such as "Medium-rare, that's warm and red in the center, right?" Often people will decide what they really want is medium.

"Medium-rare is the biggest problem, because it almost looks rare," Sullivan says.

In Morgan Hill, the 47-seat Encore Cafe also serves a good amount of steak. Co-owner and chef Kathleen Lynch has had more trouble on the rarer side. "I've had people order steak blue, but they really want it rare." (Blue is cold inside.) If she's not sure about an order, she'll go out and talk to the customer.

"From cook to cook, it is not the same. There are two basic flaws: You can't cut the meat to check doneness, and no good cook uses a thermometer."

A thermometer doesn't even necessarily help. In the book "CookWise," respected food scientist Shirley O. Corriher gives these approximate internal temperatures as guides: Very-rare: under 120 degrees, Rare: 120 to 125 degrees, Medium-rare: 125 to 140 degrees, Medium: 145 to 155 degrees, Well-done: higher than 160 degrees.

Meanwhile, the very knowledgeable Texas Beef Council's web site offers colorful photographs and "what internal temperatures to reach for your preferred level of doneness." Very-rare: under 130 degrees, Rare: 140 degrees, Medium-rare: 145 degrees, Medium: 160 degrees, Well-done: 180 degrees.

And then there is the accuracy of the thermometer.

In restaurants, meat is tested by touch. Lynch, a chef for 15 years, says, "Soft and spongy, it's rare. Harder, it's more done. Some people are better at that than others."

Corriher describes the feel of rare as "soft and yielding" and very-rare as "soft, flabby." You get the difficulty.

At Encore Cafe, steaks go into a 500-degree oven that may have 15 other occupants. The indoor temperature is affected by the number and types of other dishes in there. Also, the oven door gets opened a lot, and certain areas cook hotter than others.

The little stakes have mostly disappeared. "People were always grabbing the wrong sticks," Lynch says.

Matthew Gentry, executive chef at the Grill on the Alley in San Jose, oversees a kitchen whose output is 80 percent meat. The most popular cut is filet mignon 13 ounces in weight, 2 inches. Medium, for example, may be pinker than it's served in Cleveland. Servers are supposed to walk through the order with the customer.

This is a particularly good idea in Silicon Valley, where so many people are from somewhere else. At their favorite restaurant back home, medium may be gray through and through.

Regional preferences are very apparent to Rosemarie Elgin, co-owner of the 48-year-old Mr. Steer in Santa Clara.

People from the Midwest, for example, rarely order their meat well-done. "They love their beef," she says. "They don't mistreat it."

At Mr. Steer, if your table orders steaks done more that one way, you'll get the little stakes saying "medium-rare" and so on. If everyone at your table orders the same, and you want a stake, just ask.

The restaurant's most popular steak is the culotte, then the 8-ounce filet, the New York and Porterhouse.

They don't do blue, although if someone wants a seared steak, they'll "hit the fire quick" on both sides. She says the trend now is medium-well and well-done, "because of the news." Recent E.coli cases seem to scare people, even though steaks are at low risk for contamination.

In Morgan Hill, people are ordering both meat and fish more rare and more well-done. Extremes are in. Lynch recently had a customer who ordered a rare veal chop. So she went out to check. Few people like rare veal.

"Yep, that's what he wanted," she says.

There's no accounting for meat doneness tastes. "Some people like a crispy outside on certain cuts. I do," Lynch says. Some like a chewy texture. Or they're just afraid of red meat." Some want it cooked so much, she says, "you might as well just step on it."