One day last winter, Donal Duncan, a Portola Valley, Calif., business consultant, returned home to find a cryptic message on his answering machine. A man with an unidentifiable voice announced that he was flying up to San Francisco at noon the next day. Would Duncan visit an interesting company with him? "Call me back tomorrow morning," concluded the unfamiliar voice, "and we'll arrange details."

"I sat there and played this thing back and forth and could not understand the guy's name, other than it was John -- or Don, or Ron," says Duncan, who serves on the boards of many small companies. One of those companies is DayFlo Inc. in Irvine, Calif., and Duncan, as it happens, was then testing the company's new software product, also called DayFlo ($495).

Described by its creators as an unstructured database, the program, in effect, acts like a massive filing cabinet into which you can either organize material by "folders" or toss in information willy-nilly. But unlike a manual system, DayFlo obligingly -- and easily -- gets back what you need. To retrieve data, you simply give the program a set of criteria for its search.

So Duncan, who had already filed away close to a thousand names and addresses, decided to give the program a shot. His mysterious caller, he instructed DayFlo, had a first name that sounded like John. He probably lived in California (since he was flying up the next day), but not in the three most obvious towns in the Bay area itself. Then, on a hunch, Duncan threw in the designation "venture capitalist."

"Lo and behold," he says, "up popped two names." One person he could eliminate and the other, whom he had met briefly at a computer trade show, had a last name that "turned out, as near as I could tell, to match the grunt that I'd gotten on the recording." Armed with the information, he called the man the next morning, met with him, and, as a result, ended up on the board of directors of another company. While Duncan admits that "the guy might have called again," he still credits DayFlo for facilitating the new association.

As Duncan's experience shows, DayFlo's ability to retrieve information is unusually powerful. Still, there are other programs that can pluck data from memory. DayFlo's real distinction lies in the way it allows users to enter and arrange their material.

Existing database-management programs demand that you structure information rigidly. To set up an electronic Rolodex, for example, you might designate areas, or fields, for names, addresses, and telephone numbers. Adding another field later, such as "country," or simply jotting a note under a name would be difficult, if not impossible.

DayFlo, in contrast, lets you type in whatever you want -- at any time. And instead of requiring separate files for different kinds of data, it allows you to mix all kinds of material: numbers, invoices, text, names and addresses, random notes.

Like much of the newer software -- programs for Apple Computer Inc.'s Lisa, for example -- DayFlo strives to make users comfortable by mimicking a manager's desktop. To organize material, you create stacks, corresponding to file folders. You can have up to 20 stacks on your "desktop" at one time, containing as many as 2,500 records.

The advantages of this kind of program are obvious. Say you were working on a business plan and wanted to gather all the background you have collected on a competitorin the past six months. If you have already labeled potentially relevant data with your rival's name, DayFlo will find and immediately display the appropriate records. (lf you haven't attached a label, the program will diligently search through all the text you've generated so far, until it gets the goods. While the process takes longer, the results are the same.)

Because the software lets you enter data "at time of thought," says company founder and chairman Robert Gilchrist, it works more like people do, "not the way the computer wants to." The idea behind the development of the software, he adds, is to help managers do best what they do all day long -- "create new information out of old information."

Toward that end, you can easily transfer data to DayFlo from other programs -- any that use the IBM Disk Operating System and ASCII, the standard coding for microcomputer files. Duncan, for example, likes to record his trip expenses with Lotus 1-2-3. But Lotus's format is awkward for writing down names of companies and notes on conversations. So, with a simple "transfer" command, he just inserts the financial data from 1-2-3 to create a DayFlo record.

Later, if he needs to, Duncan can use DayFlo to search for names or dates. And now he will be able to obtain the numbers he needs for tax purposes from the same program. (He can't, however, manipulate his Lotus spreadsheet in DayFlo.)

For such purposes as writing reports, DayFlo also has sophisticated word-processing capabilities. And, in line with Gilchrist's objectives, DayFlo doesn't require you to choose a "mode" before you can carry out a particular task.

DayFlo does have one significant drawback. Because the program requires a lot of memory, it runs only on the IBM XT, the 10-megabyte hard disk version of the IBM Personal Computer.