At 8 a.m. on a cold spring day, the Cardozo-Shaw Employment Services Center at 10th and U streets NW is everything an unemployment office is supposed to be: depressing to look at, crowded with demoralized people and staffed by clerks who seem indifferent.

It has little enough to recommend it, but the need to reactivate an earlier unemployment claim has driven me here. In the waiting area, most people don't speak or even look at one another. They seem embarrassed or hostile if you catch their eye; there seems to be an unwritten rule against striking up a conversation. Here and there, a few friends chat quietly in corners; most of the others seem determinedly alone, reading, fidgeting or just staring glumly into space.

It's a motley crowd, black and white. A Yul Brynner-bald heavyset man in a gray three-piece suit, briefcase at his feet, sits next to a skinny teen-ager wearing jeans, running shoes, a wool cap and a Sony Walkman. Two small frightened-looking women in flowered housedresses confer anxiously about their paperwork with a compatriot who reads laboriously in English, then translates in rapid-fire Spanish.

A handsome, nattily dressed young man shares a copy of The Post with a burly construction worker in beer gut and overalls. A chainsmoking woman in a fur-collared coat and expensive-looking slingback pumps ignores the younger woman next to her, who holds a dimpled baby in a pink snowsuit.

The lines at the front grow from long to longer as the morning progresses. From time to time, a counselor emerges from the offices at the back and calls someone's name.

At 12:30 p.m., half-stupefied by four straight hours of reading in an uncomfortable fiberglass chair, I stumble into the street in search of food. The Florida Avenue Grill is three blocks away over bottle-strewn sidewalks, past boarded houses and unused hospital buildings.

Inside, there's another world, cozy and lively. The windows are steamy, but light streams in. Sitting at the counter, I can watch the cook. The waitresses are comfortable and middle-aged, chatting good-humoredly as they squeeze through the narrow space between grill and counter. Mine serves me a terrific breakfast of eggs, sausage, tangy stewed apples and homemade corn muffins, and keeps my cup filled with good strong coffee.

As a stranger here, I'm noticed but disregarded. Conversation among the regulars and the staff flows around me. But when I reluctantly get up to leave, the waitress grins and says "Thanks, Hon." An old-fashioned diner, it lifts my spirits, at least temporarily.

Back at the unemployment office, I discover that my name has been called in my absence, although I asked the desk clerk to keep my place. Another interminable wait looms as I leaf through the professional listings, a 69-page printout heavy on programmers, systems analysts and nurses. The list has some remarkable entries.

There is the exotic: "Import-export agent, fluent in Arabic. Two years Mideast contract and sales experience, especially Oman. $48,000." "Commodities brokers for South American copper producers. $35,000."

Then, the charmingly ridiculous: "Animal impersonator. Will dress in Easter bunny costume to take pictures with children at shopping mall in Cherry Hill, N.J. $3.35 an hour (temporary)."

Also, the romantic: "Video operator. Travel with news team to arrange technical aspects of news recording. Arrange satellite feed. French fluency. Resolves technical difficulties as they arise. $18,000." "Purchasing agent, fluent in conversational Thai and French. Travel throughout Asia to supervise purchase of ready-to-wear clothing, accessories, wholesale silks. $19,818."

I glance around at my fellow unemployed and wonder whether any of them are fluent in Thai or Arabic or even French. Where do these bizarre listings come from?

At last my name is called. My papers are apparently in order. The counselor explains the procedures, shows me the statement from my former employer, the stack of computer cards for weekly reporting. She tells me that she used to be a federal employe and was transferred to the District government a few years ago.

Now, with President Reagan in office, she thinks maybe she is better off where she is. She sees a lot of RIF victims.

She assures me that the first check on my reactivated claim will arrive later that week. "Sure it will," I think. I thank her and finally--at 3:30--I am free to leave.

Two days later, the check is in my mailbox.