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About the contributor
Duff Johnson

A veteran of the electronic document space, Duff Johnson is an independent consultant. He is Executive Director of the PDF Association and ISO Project co-Leader (and US TAG chair) for ISO 32000 and ISO 14289.
More contributions
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PDF 2.0 interops help vendors

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Why PDF?


What’s the purpose of PDF? Why don’t you just send Word or Excel files, or a link to a web page? Why bother with PDF?

It’s almost instinctive. Few think about why it’s so, but millions of people worldwide use PDF for efficient and reliable delivery of final-form electronic documents.

There’s nothing else quite like a PDF file. It’s electronic hardcopy; the digital replacement for paper.

For business and government organizations, “posting the PDF” is essentially the formal act of publication. Anyone who uses email (and that’s most people in most businesses) is generally assumed to be familiar with PDF. That PDF pages work the same way for everyone is a quiet assumption underlying tens of millions of interactions between consumers, business and government everyday.

It’s just a fact: hundreds of millions of users “PDF it” when they want to share some content.

So how did electronic paper get defined as PDF?

PDF was designed from the outset to work the same way on all systems, and it turns out that’s very important. No other format offers the same combination of attributes, but the most important of these is also the most basic.

It’s like paper.

Legal briefs, product manuals, sheet music, phone-bills, articles, construction drawings, product packaging; all may be faithfully represented, integrated and exchanged with PDF. The elemental organizational need to be able to prove it, to show documentation, to leave a readily perceivable trail – these needs imply the need for PDF in the digital world as they implied the need for printers, toner and ink in the analog.

PDF wasn’t the only contender; there were other possibilities. IBM could have released a free reader and the specification for AFP. Other “e-paper” formats such as Envoy could have made it, or HTML could have evolved to be able to take up the PDF mission. But it didn’t happen. Adobe shipped its PDF viewing software for free, and published the specification for anyone to use. The world picked up PDF and ran with it.

Could you replace PDF?

The need for hardcopy documents is almost as basic to modern economies as the need for information itself. Certainly, PDF could be replaced… by some technology that shared PDF’s capabilities and characteristics. Whether it’s the ISO 32000 we have today, or something else, the Portable Document Format concept is here to stay because persistent, shareable documentation is part of the basic set of functions that keeps the world turning, like TCP/IP, or indoor plumbing.

The need for PDF is so visceral that people don’t really think about it. We just know that when it’s important to deliver something concrete we use PDF instead of sending PPTX or CAD files, HTML pages or screen-shots.

Let’s unpack why people need PDF.

Portability: PDF is easy to share

Portability is a critical feature for any conceivable final-form electronic document format. More than any other feature, PDF is all about reliability; ensuring the same experience for the recipient as for the sender.

Unlike web-pages which depend on online resources, CSS, JavaScript and the vagaries of browsers, resolutions, window-sizes and so on, the first word in the name Portable Document Format says it all. PDF is equally at home on Windows, Mac OS X, Linux, UNIX, Android, iOS and any other operating system.

Many people do send (or post for download) a DOCX, HTML, PowerPoint or other file. These other formats, while just as easy to attach to an email, aren’t quite as easy to share as PDF. They might not look the same when opened on different machines, or may readily fail to open at all. There may be broken fonts or other application or user settings that affect appearance. There may be undesirable information such as slide-show notes, metadata or “Track Changes” information that you might not want to share. You can’t be sure the recipients have the same version of PowerPoint (or whatever you are sending). You may not want to give them the ability to edit the document, but you don’t want hassle with passwords.

Like any other technology, support for PDF varies. Few (if any) vendors implement every facet of PDF’s complete functionality, and as of 2014, broad support on mobile devices has yet to arrive. When it comes to the appearance of a page, however, PDF delivery is utterly predictable; it just works. That’s why large institutions and government agencies rely on PDF to communicate important information to end users, account holders, taxpayers and each other.

Why it matters: Portable hardcopy documents are a necessary feature of life. Nothing does hardcopy like PDF.

Easy to make

PDF files allow authors to layout and style content precisely as they see fit, using the software of their choice, confident that the document will invariably appear the same way, regardless of computer, operating system, PDF reader, software version or network connection status.

Making a PDF is usually just a couple of clicks. PDF files may be produced by any application that can print. Word-processors, spreadsheets, CAD software, scanned pages, photographs – any source content may be converted to PDF and reliably shared or stored.

Why it matters: Users learn to make PDF files from any software in seconds.

Convert from any source, use in every workflow

Also key to PDF’s success is the ability to mix PDF pages with those from other PDF documents from various sources. InDesign, Word, scanned pages, satellite images, screen-shots; they may be readily collated into a single PDF file.

PDFs are usually smaller than the files used to create them, so they are easier to email and download. Although hard-drives are getting larger and larger, a 195kb PDF file is usually preferred over a 2.95 MB Word file, especially if users aren’t expected to edit it.

Combining pages is only the necessary part. PDF includes detailed and standardized document functions, navigation features, accessibility features and more.

Why it matters: Every PDF file works with every other PDF file, so they can be shuffled and reorganized like… paper pages.

Security

PDF files are ideal vehicles for content that’s intended for limited distribution. Many PDF creation and manipulation software can add high-quality 128 and 256-bit password protection to PDF files, and even include password-protected attachments.

Why it matters: Many document authors and distributors want the security of knowing that their file can only be accessed by authorized individuals.

Authentication

The self-containment characteristic of PDF files, along with other technical characteristics, makes it possible to use standardized certificates and digital signatures with PDF files and attachments to address operational and archival authentication needs for governments, corporations and other institutions.

The digital signature mechanism for PDF is fully specified, and is available to any software developer.

Why it matters: Digital signatures make it possible to spot tampering. With a certificate authority signer, the PDF’s signer may be authenticated (or revoked, as the case may be).

Semantics

From scanned documents to drawings, diagrams and multilingual content, PDF files may be tagged to provide a complete, high-quality reading and navigating experience to users with disabilities who must use Assistive Technology (AT) in order to read.

Why it matters: For government agencies and contractors new regulations increasingly require that electronic documents be accessible. Many businesses are choosing to post accessible content to better serve disabled users. There are also many other benefits to encoding semantic information in PDF files. From data-mining to text-extraction, search-engine optimization (SEO) and more, content accessibility opens many new possibilities for interactive electronic content.

Non-Proprietary

In 2008, Adobe ceded control of the PDF specification to ISO, the International Standards Organization. Now known as ISO 32000, PDF is an International Standard. It is no longer owned by Adobe Systems. As an ISO Standard, ISO 32000 is a transparently and democratically managed, non-proprietary technology. Anyone may observe, and any member-country of ISO’s TC 171 can (and many do) send delegates to the ISO table to observe development of PDF 2.0. Members of the PDF Association may participate directly via the organization’s Category A liaison with TC 171.

Why it matters: While PDF is everywhere and the specification openly published, a lingering doubt has been the idea that Adobe Systems “owned” PDF and somehow royalties were due, or that adopting PDF for critical business functions created a vulnerability. Turning over PDF to ISO is the categorical solution to this concern – Adobe Systems or no, PDF is here to stay, and no-one owns your PDF files or your PDF software except you.

PDF viewing is always free

PDF reading software is ubiquitous in large part because Adobe shipped Reader for free from (almost) the outset of PDF. Consequently, all other PDF viewers are also free.

Why it matters: The ability to view and print documents without for free is important!


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Categories: PDF