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Data be Damn by Lynn Hanson

Nothing is more boring then a data flow diagram if you have no interest in the subject (or this article). There are thousands of data flow and signal flow diagrams, schematics, and management charts being produced by industry each day. I would base my salary on receiving a half-a-penney for each diagram produced by one good size corporation, and would need a truck to haul my earnings to the bank each week.

In the old days, BDC, that is before desktop computer, an engineer would sketch out a diagram on a sheet of paper, napkin, the back of an old memo, or whatever they had handy. Then they would give it to the draftsman to formalize.

The draftsman would draw and letter the diagram on a sheet of vellum or mylar. It had to pass the standards of the drafting room supervisor and a consistency of quality and format was achieved.

Diagrams for publication required a higher standard. The illustrator would ink the diagram on quality paper or illustrator board suitable for the photo lab. These were the days of cut and paste, when rubber cement was used by the gallon, and terms such as rubylith and Leroy where immediately understood.

The draftsman and illustrator were the 'professionals' of document design. That was their job, to produce quality documentation.

Today, designers produce their own diagrams on desk top computers; each carefully crafted, each entirely different. The individual rules, long live Ayn Rand. The drafting room for the most part, and the illustrator's department to a lesser degree, no longer work as filters. Consistency and quality in documentation was lost.


The data flow diagram remains a necessary and important element of design. When done right and distributed to the design community it distills complex information in a style that's easy to comprehend.

When drawn applying poor design practice; lines crossing lines, unrelated information, overuse of acronyms, small text that's hard to read, then information is obscured. For all practical purpose the diagram is useless and creates a void.

A little knowledge goes a long way. There are standards by which diagrams are drawn. Character style and size, white space, info box alignment, line weight, and symmetry are all important elements of document design.

But then, we can get by, cant we? We wouldn't confuse meters with feet, or wire a switch backwards, would we? Aren't we saving bu-cu bucks by eliminating positions and keeping our engineers busy?

We can't, nor would we want to, go back to the old days. However, a little document review and instruction would go a long way in creating useful diagrams and eliminate errors in design.


A Simple Data Flow Diagram

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