A pocket-sized way to pledge allegiance to the flag of Sox Nation

If your three Red Sox baseball caps, ''World Champions" sweatshirt, Johnny Damon tank top, souvenir David Ortiz bat, and matching his-and-her Bosox bathroom towels are not enough to broadcast your allegiance to the hometown team, then Major League Baseball has just what you need: an official, wallet-size membership card to ''Red Sox Nation."

Starting sometime this week, Red Sox followers will be able to register themselves or friends as ''citizens" of Red Sox Nation through Major League Baseball and Boston Red Sox websites. For those who register early enough, membership cards will probably arrive in the mail before Christmas.

Fans will have to pay a registration fee of about $5 -- apparently decades of heartache are not payment enough -- but team officials stress the membership drive is not a gimmick to help pay Pedro Martinez's salary. The goal, instead, is to try to assess how many Sox fans there are worldwide -- from California to the Dominican Republic to the Iraqi theater -- in the aftermath of the Sox' captivating playoff run and World Series victory.

How many fans could there be? Team officials would not offer a guess. ''The citizens of Red Sox Nation will make the size of their chorus known to us," said spokesman Charles Steinberg. Aside from issuing cards, the team could potentially choose batboys and batgirls from among participants, or display the Red Sox' championship trophy in communities with significant numbers of fans.

However, some Sox loyalists are blasting Major League Baseball for charging a fee for the card. ''If you pick up a newspaper or buy a ticket or watch NESN, or if your grandfather went to the games, you're already an official member of Red Sox Nation," said Steve Silva, founder of the Boston Dirt Dogs fan website, now owned by Boston.com. But other fans -- perhaps millions -- might jump at the chance to add a card to their wallets, especially one with the words ''World Series Champs."

PETER DeMARCO