Naming a restaurant is never easy. It's the most visible evidence of a brand, an attempt to set the mood and tone of the enterprise.

But no one could ever accuse restaurateurs of originality. Not long ago in the Philly area, there were at least three Michael's restaurants - the casual diner chain in the burbs, a bistro on Chestnut Street, and an Italian restaurant in Bella Vista. (Only the diner chain remains.)

The now-gone Bookbinder's Seafood House, spawned from Old Original Bookbinders after a family feud, managed to coexist, albeit uneasily, across town from each other.

Only rarely does the matter end up in court. The Bards, an Irish pub, was known as The Irish Bards when it opened in 1996 next door to the Irish Pub at 20th and Walnut Streets. The Bards dropped "Irish" after the Irish Pubs sued.

In Montgomery County, as noted recently, two guys with three restaurants that include the word Feliz in the name have gone to federal court in an attempt to bar a rival from using Feliz in the name of his nearby restaurant.

Which gets me to Chinatown, where a restaurant specializing in the cuisine of the city of Xi'an opened last week at 902 Arch St. with the name Xi'an Famous Food. In researching, I found Xi'an Famous Foods, which has several locations in New York City and some national publicity behind it. Staff at the Chinatown location would not provide information, but the owner of Xi'an Famous Foods in New York said that his restaurants were not related to the newcomer and that he was contemplating legal action.

Up the street, a noodle bar/karaoke lounge called Tango opened last week. The Tango at 1021 Arch St.  has nothing in common with Tango, an American bistro that opened in 2000 at the Bryn Mawr Train Station.

It doesn't matter if the second restaurant is deliberate or accidental in the name choice. The key to a trademark lawsuit's success is the potential of confusion, which is why careful restaurateurs search copyright and trademark databases before committing to a name.

Jose Garces, for example, wanted to use "Chilango" - the nickname for Mexico City residents - for his restaurant that opened five years ago at 40th and Chestnut Streets. His counsel discovered a restaurant by that name in Atlantic Highlands, N.J., so it became Distrito - after Distrito Federal, the proper name for Mexico City.