The importance of modern man's orientation towards documents has shaped much of the evolution of computers. For decades, the principal role of computers in business was data processing, which consisted almost entirely of summarizing large amounts of data onto paper documents. The advent of word processing, in which printed text documents could be created as such, gave rise in part to the mini-computer revolution of the 1980s, in which all businesses began to adopt computers in house. Today, word processing remains one of the principal defining activity of PCs. The word processor is second only to the browser as the most used software on most PCs. (The browser itself, of course, is a page-oriented device.)
But as the nature of computing has changed in the last decade — from PCs to devices with smaller form factors — the shape of documents has begun to change in concert. And this evolution has important, long-term implications for developers.
For most of the last century, documents enjoyed a stable form factor. The DIN system used in most of the world outside the US was devised almost 100 years ago and adopted relatively quickly. The DIN A4 sheet, roughly equivalent to the US "letter" size, is one of the most universal of formats, both in its dimensions (210mm x 297mm) and its orientation (portrait). In the US and Mexico, the so-called letter size predates DIN and has been in continuous use for probably centuries.
The stability of the form factor and the archival, historical quality of hard-copy documents derives from a quest for a certain kind of defined immutable format. This belief in the need for immutability is in part what attracts us to PDF documents: If all fonts are embedded, the PDF will look the same on all systems that can render the format. (This is almost completely true — true enough that it provides the experience we expect.) The PDF/A format — an extension to PDF — specifies a basic set of features that Adobe hopes will allow PDF documents to be read decades, even centuries, from now.
Hardware technology, however, is moving in a different direction. This divergence is eminently clear in eReaders today. Unless you're a hidebound traditionalist with no technophile friends, you've surely held an eReader in your hands and watched the page size change as font size is increased. Actually, page size stays the same, but the number of words per page changes. On some readers, such as the iPad, the actual page number changes on the screen with each change in font size. Such that, the concept of, say, starting to read at page 145 is now insufficient. It's page 145 at font size x. This fluidity of form is even more pronounced on readers that run on smartphones.
The orientation of documents has changed, too. For example, the monthly PDF version of Dr. Dobb's Journal (you do subscribe, don't you?) now ships in landscape, rather than portrait orientation. This satisfies the two principal reading devices we anticipate: landscape-oriented screens sitting on desktops, and the iPad.
Comments I've received on this design, which we began three months ago, have been almost exclusively favorable.
This PDF version of Dr. Dobb's, however, will probably give way to eBook formats in a few years. I expect that within the decade, completely reformattable documents will become the norm, rather than the sole province of leisure reading as it is today.
In a literal sense, this evolution can be accurately termed the disintermediation of the document. Because content can be so radically separated from the vehicle by which it is borne, the vehicle has become an interchangeable artifact. I have no difficulty imagining a world in which our children will look at PDF documents with the same admiration and sense of an earlier, simpler time that we feel today when gazing at handwritten letters and records.
For developers, this fluid form creates several problems. The fewer assumptions about presentation constraints, the better. Users forced to read documents in a way that does not accommodate their preferred viewer will accurately consider the limitation a serious design flaw. You can already experience this frustration today trying to read PDF documents on a Kindle. Without a reflow capability, the experience becomes tedious quickly. This is a problem we've already covered once (see "Displaying Tabular Data on iPhones") and whose ramifications we will surely cover many times more in the near future.
— Andrew Binstock, Dr. Dobb's Executive Editor