IN THE film When Harry Met Sally, we find Meg Ryan has recently broken up with a longtime boyfriend. Over lunch, Carrie Fisher tries to cheer her up by promising to help find a new one. Pulling a Rolodex out of her purse, Fisher rummages through a file marked ''single'' and hands her the business cards of potential dating material. Although we all know there are no single men of potential dating material in the real world, I was nevertheless impressed with the Fisher character's ability to organise her business cards. Before I discovered a Rolodex, I used to keep business cards under the legs of my furniture, filing the ''S's'' under the sofa. I relented when my friends pointed out a sunken living room didn't mean furniture raised half a metre above the floor. Looking at the piles of business cards I had accumulated over the years, I realised that in Hong Kong, one was made to feel naked without one. These tiny pieces of paper with someone's name, title and company details have evolved into a proof-of-identity card in the Hong Kong business world. They are required by unnatural law to be carried at all times and surrendered on demand by any member of the business community. Business cards have become more of a daily necessity than tissues. Supporters point out business cards are more practical because they can double as both. Without a card, you raise suspicions that you may be an ''II''. ''Illegal idlers'' have been known to lie about their jobs and, when asked for a card, they pretend to have left them behind. Because the Government has strict regulations regarding the alteration of identity cards, the business card becomes an easier method of lying about who you really are. On a piece of card, the dustman is a ''sanitary removal engineer'' and the ice-cream man becomes a ''soft goods distributor''. Others have taken to putting random letters at the end of their names, to add an educational dimension to their persona. When it comes to business cards, some mistakenly assume bigger means better. THOSE who find themselves in possession of an oversized card will have realised they do not fit in a normal-sized Rolodex and will eventually end up as coasters or exercise mats. Overly ornate cards do not always impress either. Contrary to popular belief, a platinum card from a bald billionaire will not stop a person from thinking: ''Gee, get a load of that head of skin.'' Once they are harvested, some like to organise their business cards alphabetically. Others, like my friend Sutra, prefer to file them in categories. While rummaging through her cards one day, I noticed the headings ''echo'', ''Santa Claus'', ''Don Juan'' and ''dice game''. ''What do these mean?'' I said. ''Echoes are bores; they always have to have the last word. Santa Clauses are guys who won't leave a woman's stockings alone.'' ''Does that mean all the exciting men you've met are in the Don Juan category?'' I interrupted. ''Don't be silly; it means I Don Juan anything to do with them.'' I hated to ask, but I did: ''And dice game?'' ''Oh, those are people who are full of c***.'' ''What's this pile marked fun ?'' I inquired. ''Well, if a guy is hassling me at a disco I hand him someone else's card and tell him to call me at work. Sometimes, if I don't like someone, I use their card to enrol them in a lonely hearts' club or put them on a mailing list for a religious cult.'' Ultimately, the function of the business card is to help remind you of the people you meet. Unfortunately, most of us are left with a pile of business cards bearing the names of faceless people. But instead of throwing these seemingly useless business cards away, keep and study them. There's always the chance that one day when you're chatting to someone you can't remember, you'll look down at their card, your face will brighten and you'll say: ''I'm sorry I can't recall you, but your business card looks familiar.''