For Stephanie Jones, picking a sunscreen used to be as easy as counting to 30. She pulled out the Water BABIES and slathered it on daughters Jordan, 6, and Brooke, 4 months.

Now, dermatologists are attempting to re-educate sun lovers. SPF still matters, they say, but it's not the whole story.

To pick a sunscreen in 2007, you also need to know your UVB from your UVA, and the term "broad-spectrum protection." You also may have to read an ingredient label or two.

The Jones family, of Kunia, is already in the sunscreen habit with Jordan.

"Since she was a little girl, we always put sunscreen on her before we leave the house," Jones said, "not because that's what it says on the sunscreen, but because it's easier."

And yes, they'll don sunglasses and reapply as needed. Now they're getting their sunscreen alphabet straight for full solar protection.

Ultraviolet light from the sun comes in several wavelengths: UVA, UVB and the rarely discussed UVC (which is blocked out by the Earth's ozone layer). UVB, which damages the outer layer of the skin, has been recognized for decades as the cause of sunburn and as a major contributor to skin cancer and skin aging, said James Spencer, a dermatologist in St. Petersburg, Fla.

"When sunscreens were developed, they were made to prevent sunburn" and targeted only UVB, he said. An SPF number refers to the UVB burning protection a product offers (one with an SPF of 15, used correctly, allows the user to stay in the sun 15 times longer without burning).

But recently, scientists have learned that UVA rays, while not contributing to sunburns, damage deeper layers of the skin and probably play an important role in wrinkling, spotting, lost elasticity and, most ominously, the dangerous skin cancer melanoma.

"Ten years ago, a lot of people thought UVA didn't do anything," Spencer said.

"But now we understand that there's an interplay between UVA and UVB, with UVA (magnifying) the effects of UVB," said Susan Weinkle, a dermatologist in Bradenton, Fla.

That's a big problem, she said, because UVA rays, unlike UVB rays, are equally potent year-round and at all times of day, and they pass through windows. So UVA damage, she said, is a more constant threat.

Honolulu dermatologist Dr. Carla Nip Sakamoto adds that not all sunscreens are created equal, especially in our land of year-round sun — and especially for Isle outdoorsy types.

"We probably have to be extra conscious about sun-protective behaviors," she said. "Sunscreen is part of that, but it's not the whole story."

She advocates protective clothing, eyewear, even headwear — even if, as some might say, "hats look goofy in the water," Nip Sakamoto said.

"I think it is important that our population be diligent in understanding the differences in sunscreen and knowing about wearing sunscreen," said Nip Sakamoto, who practices what she preaches, putting on an SPF of 30 every day.

Sunscreen makers are paying attention and offering more "broad spectrum" products with UVA blockers. The most effective ones include at least one of three ingredients: avobenzone (also called Parsol 1789), zinc oxide and titanium dioxide.

Each ingredient has flaws: avobenzone breaks down in the sun, and the other two can look thick and opaque on the skin. None filters out the entire spectrum of UVA rays.

But manufacturers keep tinkering, coming up with formulas such as Neutrogena's "Helioplex" that stabilize avobenzone or that use more transparent forms of zinc oxide and titanium dioxide.

A breakthrough came last summer when the Food and Drug Administration approved Mex-oryl SX, a chemical long used in Europe that blocks short UVA rays missed by other sunscreens. It's patented by L'Oreal, which has introduced two pricey products using Mexoryl SX combined with a stabilized form of avobenzone. One is La Roche-Posey's moisturizer Anthelios SX ($29 for 3.4 ounces); the other is Lancome's water-resistant UV Expert 20 face and body cream ($35 for 3.4 ounces). More products are in the pipeline, said Alan Meyers, L'Oreal USA's senior vice president for research and development.

Nip Sakamoto said her patients are asking about Mexoryl SX, which can be ordered online.

"The technology is really exploding" and eventually will offer consumers even more choices, Weinkle said.

A standard ratings scale for UVA protection similar to the SPF number for UVB also is in the future, experts said.

And the Jones family will be ready.