Here are a few of the rules, recently codified and updated so that newcomers can start right in and celebrate the quintessential Seattle Thanksgiving:

Carbo Load Corollary. Puget Sounders planning to enter this weekend's Seattle Marathon - Marymoor Park to Gas Works Park - will be first in line for seconds of mashed potatoes, sweet potatoes, dressing and gravy. Considerate hosts schedule a light run between courses.

Christmas Convention. No matter how old you are, if you are attending a family event in the Puget Sound area, you will be told: "Don't forget. Bring your Christmas list to Thanksgiving dinner."

Conversation's Gambit. Topics other than the weather will include (1) sailing, (2) skiing, (3) backpacking or (4) trips to other parts of the country for the purpose of sailing, skiing or backpacking.

Dress Code. You know you're celebrating in Seattle when your guests don Puget Sound tuxes. This means that jeans are acceptable, if not too badly torn. Wearing black tie with Gor-Tex jacket is permissible, but three-piece suits and wingtips are out. Save them for slumming in the financial district.

Elbow's Law. Local custom calls for every left-handed diner to be seated to the right of a right-handed diner, maximizing chances for collisions and spills.

Gravy's Constant. The silver gravy boat - a wedding present from Great Aunt Agatha - will vanish before the meal. It will show up next summer when you're looking for the water skis.

Melmac's Discovery. At least two distinct patterns of dinnerware must be visible on the table at every course.

Pudding's Rule. Real traditionalists will insist on pioneer corn pudding, the kind that you make by combining a can of creamed corn, one egg, two-thirds of a can of milk and crushed soda crackers and then baking.

Old-timers' Lament. Someone in the group - middle-aged or older - will say it's a shame that there's no longer a Turkey Day football contest between Seattle and Puget Sound high school champs.

Pollyanna's Principle. Guests will include at least one orphan - someone from out of town who can't make it home for the holiday. Or, if no orphan is available, one oddball can substitute.

Salad's Law. Salads, supplied by Thanksgiving guests, always arrive with excess moisture. The soggy additive usually is supplied by the ambient rainfall. However, if it should merely be overcast on Turkey Day, the host or hostess should add water before serving.

Snow's Panic. Should there be a trace of snow, one half of the dinner guests will leave early to wax their skis, the other half will leap up in the middle of the meal suffering from acute snow panic. (Will they ever get home?)

The Cranberry Convention. An unmolded can of cranberry sauce must be on the Seattle Thanksgiving table. No one is allowed to touch it. But, should the cook overlook the sauce, everyone will complain.

Watson's revenge. A venerable Seattle columnist - now in the pay of Brand X - annually escapes writing a column by reprinting directions for the Thompson Turkey. The recipe calls for smearing the turkey with mustard, then roasting the bird until its charred legs fall off. No one has ever eaten a Thompson Turkey and lived to tell about it. But that's understandable because no one has ever actually baked one of the things either.

Jean Godden is a staff columnist who writes three times a week in the P-I.

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