A pair of pretty good Bordeaux was on the table I shared with friends at Tribeca Grill on a recent Monday evening. One was a Pomerol, Chateau Le Bon Pasteur 1998, the other a St. Estephe, Chateau Montrose 1990. If those wines had come from the restaurant’s well-stocked cellar, they’d have added at least $900 to the tab before tax and tip. Ouch! But we paid just for the food, because Monday nights at Tribeca Grill (375 Greenwich St., between North Moore and Franklin streets) are BYOB, with no corkage charge added.

Those four capital letters, more familiar at frat parties than at a raffish café on Greenwich Street, are sweet music to those of us who aren’t on an expense account — after all, a wine tab can easily dwarf the cost of the plated food. BYOB Mondays is an unadvertised policy at Tribeca Grill. Based on the bottle bags unloaded at the tables around me, wine buffs are tuned in. Tribeca Grill’s Monday wine policy is, I suspect, a consolation gift from proprietor Drew Nieporent, who in 2006 shut down Montrachet, his pioneering Tribeca spot where BYOB Mondays created a tradition of sharing sips between tables, even with perfect strangers. Surprisingly, Manhattan is filigreed with BYOB restaurants that forego a corkage fee. At many others, the charge is under $30. But one must be proactive in identifying these spots and in hewing to their house rules when it’s your bottle instead of theirs. It can get complicated. The charming West Village outpost A.O.C. Bedford (14 Bedford St. at Minetta Lane), for example, allows you to BYOB any day — but in this instance, it stands for “bring your one bottle” for every two people. And only one. Additional sipping must be done from the wine list. Smith & Wollensky (797 Third Ave. at 49th Street) is a corkage-free BYOB steakhouse, so long as your bottle isn’t on its wine list. La Grolla (413 Amsterdam Ave. at 80th Street), as I learned the hard way, is BYOB so long your tab exceeds $50. My food bill for a recent simple pasta supper totaled just $48, and so a $20 corkage fee was added. Buying two espressos would have eliminated that charge.

Chinatown, where many restaurants don’t have liquor licenses or even a corkscrew, is fertile BYOB turf. I head for the seafood mecca Fuleen (11 Division St., between Catherine and Market streets), where I recently enjoyed an iced platter of thin-sliced, giant clam meats that played perfectly with an Oregonian Ponzi Pinot Gris 2006. Fuleen’s diffident waiters can bring a flapping fish from a live tank to your table, but not an ice bucket, so advance planning is required if the white wine is to be properly cool. My strategy is to over-chill my white wine, especially now in summer, before packing it in an insulated wine bag for the trip downtown. Some BYOB buffs obsess over the quality of glassware into which their wine will be poured. Yes, that’s part of the pleasure factor, and some restaurants even allow BYOS (bring your own stemware), including Fuleen. What’s more important to me, frankly, is how the staff reacts when I hand over the wine that I brought from home. If they act as though they’re doing me a favor, why bother to have a BYOB policy? One SoHo spot with an exemplary attitude is Ivo & Lulu (558 Broome St. at Varick Street), a needle-narrow bistro where a young waiter actually smiled when I presented him a bagged bottle of Cloudy Bay Pinot Noir 2004.

Among the restaurants that charge a modest BYOB fee, I’m partial to the SoHo stalwart Zoë (90 Prince St., between Broadway and Mercer Street). Not only is the welcome warm from co-proprietor Stephen Loffredo, but he loves to gab about the grape. He may even pour you a sample of something terrific from the wine bar. The corkage fee at Zoe is $15, and the stemware is handsome. The same fee is charged at Fairway Café, a relaxed retreat one flight up from the bustle of the Fairway Market (2127 Broadway at 74th Street). Its own brief but balanced wine list, edited by wine consultant Willie Gluckstern, is so well-priced that it hardly makes sense to bring your own unless you have a particular bottle you’re anxious to try with the very fresh ingredients sourced directly from the vast market downstairs.

I have yet to find any restaurant’s menu or Web site that explicates its BYOB policy, so it’s always best to call ahead to get specifics — especially for restaurants that have just opened, and are BYOB merely because their liquor license has not been granted yet. Several Web sites track local BYOB restaurants, the most complete of which is tastersguildNY.com/byob.shtml. The site lists more than 100 restaurants with BYOB options, many of which, however, carry stiff corkage fees.

A few points of BYOB etiquette: Don’t be shy about taking advantage of a restaurant’s BYOB policy. The restaurant may be losing a wine sale, but it’s gaining customers who might otherwise go elsewhere. Take care to tip your server as if the wine were on the check. Don’t hesitate to order a bottle from the wine list, or even a glass of bubbly as an aperitif, to augment your own carry-in. Finally, if the wine is worthy, save the last pour for the server, who may be forbidden from tasting in view of diners, but who can put the bottle away for later. Your generosity may even cause him or her to “forget” any corkage charge on your bill.