Challenges Ahead for Adobe's Portable Document Format

Volume 21, Number 2 - April 2005 through June 2005

Challenges Ahead for Adobe’s Portable Document Format By Dr. Paul Cesarini and Mr. Jason Mellen

Peer-Refereed Article

KEYWORD SEARCH

Computer Technology Graphic Communications Information Technology Internet Philosophy Visual Communications

The Ofﬁcial Electronic Publication of the National Association of Industrial Technology • www.nait.org © 2005 Journal of Industrial Technology • Volume 21, Number 2 • April 2005 through June 2005 • www.nait.org Challenges Ahead for Adobe’s Portable Document Format By Dr. Paul Cesarini and Mr. Jason Mellen

Introduction: that it will become the mainstream the Promise of PDF technology for electronic communi- Dr. Paul Cesarini is an Assistant Professor in the Department of Visual Communication & Technol- Universal document exchange, that cations, document distribution, and ogy Education (VC&TE) at Bowling Green State elusive goal only slightly less far- printing / publishing workflow.” (p. 61) University. His current research and work focuses on digital rights management and the on-going fetched than the paperless office, has While the author agrees with his overall erosion of fair use for audio, video, and text. Prior largely become a reality over the past premise that the PDF is robust, mature to teaching in VC&TE, Paul created and managed the BGSU Student Technology Center, Laptop Loan few years. Adobe’s Acrobat line of technology with great potential, it may Program, and annual Technology Fair. He reads not be quite so clear-cut. Wired far too much. products, recently released in their 7.0 incarnation, have steadily improved and have achieved a near-ubiquity in a va- Despite overall gains in ease-of-use and riety of industries and disciplines. The a broad user base, the PDF now faces a publishing industry continues to rely series of hurdles and roadblocks toward on Acrobat for all things print. Web its very universality. These include the content developers and technical com- potential for malicious code to be in- municators rely on it for convenient troduced into PDFs, increased usability and efficient ways to make manuals concerns associated with PDF-based and related documentation accessible to content online, the continued lack of end-users. Adobe has recently begun standardization in the electronic book pushing Acrobat as an essential tool for (eBook) industry, overall readability on enterprise, as well, by promoting it as computer screens or web browsers, and a foundational tool for accessing and stiffened competition from several key sharing corporate data. players in different industries, includ- Jason Mellen is a student of Visual Communication ing Microsoft, Macromedia, Palm, and Technology and a Digital Media Technologist with Autodesk. Bowling Green State University's Digital Media Re- Creating a portable document format search Group. Jason's research and work focuses (PDF) file in many cases has now be- on the areas of digital media, e-Learning, and An Open Specification, computer-aided collaboration. He also serves as come as easy as printing, and often in- the resident advisor to IMPACT, a living-learning volves little more than a single mouse- a Broad Base community focused on the integration of moral How has the PDF managed to become principles and critical thinking. click. This is a far cry from earlier versions of Acrobat that often involved so widely used in such a relatively short complicated distillation processes and period of time? The PDF is barely over intermediary file formats to get from a decade old, yet its reach is both far the original to a PDF. Adobe has also and wide. The open licensing stance made it increasingly easy to transfer a taken by Adobe has a great deal to do PDF file to a Palm OS or PocketPC- with the success of the format. Adobe based device, which further enhances does not charge a fee for their PDF the portability and appeal of the format. format. Adobe has often stated that “the PDF is available to anyone who This increased ease of PDF creation, wants to develop tools to create, view, and corresponding overall popularity of or manipulate PDF documents,” and the PDF format itself, has not gone un- has gone so far as to openly publish the noticed. In Portable Document Format PDF specification, in order to encour- (PDF) – Finally, a Universal Document age development of third-party PDF Exchange Technology, author Wan-Lee solutions. The following legal notice Cheng espoused the likelihood of long- from Adobe’s Developer Solutions site term sustainability and growth in popu- relates to this openness: larity of PDF. He states that, “Although PDF is still growing, there is no doubt

2 Journal of Industrial Technology • Volume 21, Number 2 • April 2005 through June 2005 • www.nait.org

Adobe desires to promote the use of on Windows-based platforms, and in XML has certain advantages over other PDF for information interchange all likelihood Microsoft will never opt binary data formats. For one, XML files among diverse products and ap- to incorporate this feature, Adobe has are human readable in that the content plications. Accordingly, [seven] . . compensated for this by releasing a is understandable in its raw format . patents are licensed on a royalty- barebones version of Acrobat exclusive without special machine formatting. free, non-exclusive basis for the to Windows, called Acrobat Elements. Additionally, because every XML term of each patent and for the sole For about $50, Acrobat Elements document conforms to a given struc- purpose of developing software that provides a minimalist feature set that ture, the data can be exchanged and produces, consumes, and interprets effectively gives Windows PDF feature validated using generic XML parsers PDF files that are compliant with parity with Mac OS X. Adobe touts and exchange systems (such as XML- the Specification (Adobe, 2003) this basic level of PDF functionality as RPC). (DuChame, 1999) The open being a way for businesses to “extend nature of XML data makes it easy to These actions have allowed the PDF the value of their Microsoft Office share single data sets among different to flourish in Open Source Software investment by standardizing on Adobe applications. An example would be a (OSS) products such as the free Ope- Portable Document Format (PDF) for meeting agenda for an enterprise corpo- nOffice.org suite, which allows for on- reliable document distribution.” (Ado- ration that contains XML information the-fly PDF and Flash conversion with be, 2004) Third-party companies have about both attendees and the meeting any documents generated by its word also made in-roads here, as well. Com- itself. A calendaring program would processing, spreadsheet, presentations, panies such as Xelerate, Data Becker, interpret the relevant XML in order to or web-authoring components. Scansoft, and others have released add the meeting to a user’s calendar. inexpensive software for Windows that Meanwhile, a user’s contact manager OpenOffice.org Community Manager allow basic PDF creation. The open would parse information about the at- Louis Suarez-Potts clarified this license source community has also stepped-up tendees and add that information to an somewhat. According to Suarez-Potts, in this area, by developing free PDF address book. while not necessarily an open standard, generators like PDFCreator. which often implies a peer review pro- Given the powerful nature of XML, cess, and certainly not open source, PDF The Strength of XML Adobe’s adoption of this data format is indeed an open specification. (Louis Recently, Adobe has taken steps to will likely push the PDF format in new Suarez-Potts, personal communication, achieve a new level of openness with directions and take the platform into January 14, 2004) Adobe spokesperson the integration of the Extensible uncharted waters. Adobe’s XDP files John Cristofano further added to this Markup Language (XML) data format will use XML to represent four types of idea in Mozilla Magazine. He stated into their PDF platform. A new meta- information: form templates, form data, that “PDF is a published specification format called XDP (XML Data Pack- configuration information, and other - meaning it is publicly available for age) combines traditional PDF files information such as digital signatures anyone to acquire; anyone who acquires with XML markup that can contain and meta-data as well as the traditional the specification has the capability to both information from the document PDF data. Form templates provide the create programs that read and/or write and information about the document. technical descriptions and field-map- PDF files.” (Angelo, 2003, p.2) (Adobe, 2003b) XML is a multi-pur- pings used when linking XML data pose file format for the representation to form fields in the PDF documents. This openness and broadly-installed of “data objects.” To understand XML, The form data is the actual vocabular- existing user base were likely deciding it is perhaps helpful to first think of ies (like ACORD) that are used in the factors behind Steve Jobs’ decision to Hypertext Markup Language (HTML); document’s embedded form fields. The base the 2D rendering library of Quartz, the language of the web. HTML “tags” XML configuration data is responsible the primary imaging model of Mac OS are used to indicate various styles and for various databases and SOAP con- X, on Adobe’s PDF format. As a result, attributes within a document. However, nections for that document. SOAP is a PDF is the default file format of Mac HTML contains a limited vocabulary protocol used for exchanging informa- OS X, and anti-aliased text and graph- that is understood by web browsers tion with web service applications. ics within Mac OS X is significantly for displaying documents. XML, in improved from previous versions of contrast, has no specified vocabulary. The ability to have information con- the Mac OS. Additionally, OS X users Rather, it is a file format to which vari- tained within PDF documents ex- can generate a PDF output from within ous, context-specific, vocabularies may changed with web applications is what any application, rather than hardcopy, be applied. (DuCharme, 1999) For has the most potential to reposition the without having any version of Acrobat instance, the insurance industry has a format in the marketplace. Imagine a installed. standardized vocabulary, ACORD, for product distributor issuing a Request exchanging information in XML files for Proposal in an XDP document. While this degree of native PDF while healthcare organizations utilize Each supplier would have a customized conversion is currently not possible the HL7 vocabulary. (Adobe, 2003b) document based on the XML embed-

3 Journal of Industrial Technology • Volume 21, Number 2 • April 2005 through June 2005 • www.nait.org ded in the file. That supplier would then sibly, but not necessarily. Technologist systems. These virus hoaxes are propa- fill out the RFP form and select the Richard Hoffman perhaps best explains gated by way of seemingly helpful submit button. Processing instructions why such a technological monoculture email messages warning users to search within the document would validate should be avoided. In Resisting the Path for and delete specific files on their sys- the information and then send it to the of Least Resistance, Hoffman states: tems, purportedly containing viruses, computer systems of the distributors. but which are actually essential files The final products would still be exact A monoculture tends to be fragile needed to keep the system running. copies of the RFP forms complete with because of its sameness. Perhaps In each case, the delivery mechanism the updated data. However, the data more importantly, however, a mono- or catalyst somehow involves a Mi- has already been sent and processed by culture is by nature slow to adapt, crosoft product. It is not likely due to the distributor by the time the supplier change and innovate--particularly Microsoft’s products being less secure could even hit print. (Adobe 2003b) in the case of the computer industry. than, say, a Mac OS X system. Rather, The PDF framework also has security What incentive is there to really in- the Microsoft products present a larger measures in place to allow for encrypt- novate when your only competitor is target virtually guaranteeing the virus ed exchange of information as well as yourself? All you need to do is make will spread quickly. As such, the vast the authentication of users via digital slow, incremental changes just often majority of viruses and worms actively signatures. Adobe has developed part- enough to assure a steady supply of affect only Windows-based systems. nerships with leading digital security upgrade revenue. (Hoffman, 2001) Yet, if PDF were somehow eventually firms such as RSA, VeriSign, Entrust, used to propagate viruses, the effect and ActivGaurd. (Adobe, 2004b) The Of course, continued innovation in the could be significantly more troubling, addition of XML data into PDF will PDF monoculture has not yet stalled. and could spread significantly more move the format from that of a mere In addition to the previously mentioned quickly: every Windows-based system, transporter of static documents to a XML integration, Adobe has steadily Mac OS X-based system, Linux-based platform for the exchange of enterprise increased helpful features such as system, and nearly every PDA could information. tagged PDFs (which reflows text in potentially be a carrier. If this were to PDFs to suit different devices), addi- occur, the primary selling point of PDF The Trouble with Universality tional commenting options, and more –universality– could well become the This ongoing integration of XML into advanced digital signature capabili- primary problem. the PDF specification will most likely ties. Yet, Hoffman is not alone in this only help make the PDF itself become view. In The Ecology of Computer Such a scenario recently surfaced in even more widely diffused, with an Viruses, Jamais Cascio argues that "The the PDF monoculture. In August 2001, even broader user base. Yet, while this relentless spread of a single platform, a new virus known as “Peachy” used broad user base may be the strongest steadily incorporating more and more PDF files as carriers. The Peachy virus asset of the PDF, it also has the poten- interrelated 'features,' marginalizes, used Acrobat’s well-documented at- tial to be its chief source of problems. pushes out and finally kills its eco- tachment feature, which allows em- Rob Lancaster, a technology research logical competition -- in turn creating bedding of files within PDF, to spread analyst for The Yankee Group, recently the very monocultures that leave the malicious code. Peachy was a rather voiced concerns about the PDF. He software vulnerable to subversion." tame virus, particularly when compared stated that “a big part of that appeal (Cascio, 1999) to newer, highly virulent worms and vi- [of PDF] rests on the ubiquity of the ruses such as Sobig, Mydoom, and Du- viewing capability.” (Becker 2003) Both Hoffman’s and Cascio’s com- maru. However, regardless of the mild That is, the ubiquity or universality of ments dealt with a different monocul- outcome of Peachy, it caused serious the PDF is its primary strength and its ture: Microsoft. Yet, much of their concern. In New Virus Travels in PDF primary appeal: it is universal, so it is views could hold true for Adobe’s PDF Files, author Stephen Shankland states widely-used; since it is widely-used, it specification, as well. The more uni- that “the Peachy virus raises the issue is universal. To appropriate an agricul- versal PDF becomes, the more appeal- that PDF files--widely used to display tural term, PDF appears to be steadily ing it becomes as a potential target for documents within Web browsers and e- evolving into a monoculture malicious code. Think about current mail--could become a new channel for file types used as delivery vehicles for spreading viruses.” (Shankland, 2001) What, then, is the problem? If a critical viruses and worms: Microsoft Word Similar concerns have been voiced by mass of users adopt the software or file files have served as carriers by way others. Richard Smith, Chief Technol- format of a certain company, which of Word macroviruses; email viruses ogy Officer of the Privacy Foundation, in turn forms a defacto standardiza- / worms have propagated largely by expressed alarm that this event might tion within different disciplines and/or using Outlook or Outlook Express as not be isolated, and that it could in fact industries, would not such standardiza- delivery mechanisms. Additionally, be a “new frontier” in virus distribution ultimately be for the best? Pos- so-called “social engineering” virus tion. (Shankland, 2001) hoaxes have targeted Windows-based

4 Journal of Industrial Technology • Volume 21, Number 2 • April 2005 through June 2005 • www.nait.org

In April 2003, another PDF-based “considerably smaller than PDF and the e-book business operates today. virus surfaced. The W32.Yourde virus easier to share with downstream users” (Nucci, 2002) infected files opened and saved in the and adds that “when it comes to distrib- full version of Acrobat, by exploiting a uting design data, nothing beats DWF Quan echoes this statement in E-books vulnerability in the Javascript parser of – not even PDF.” (Autodesk, 2003) Face Standards, Copy Protection Is- Acrobat. While the Symantec Antivi- Autodesk claims DWF files can be sues. She states that “The lack of a rus Research Center (SARC) rated the created and accessed quicker than PDF standard file format is a barrier to mar- Yourde virus as being a “low” cause for files, which in turn would lead to more ket growth, since publishers currently concern, and the malicious code only convenient and efficient review times for converting printed texts must undergo affected Windows-based systems, the projects. On their web site, Autodesk the time-consuming and costly pro- end result is still troubling: the PDF even includes customer testimonials that cess of accommodating divergent file was used as an efficient mechanism for openly disparage the PDF, claiming it is formats for different reader systems.” virus distribution. ill-suited for mechanical design. (Au- (Quan 2000). Admittedly, the eBook in- todesk, 2003) dustry has been and likely will continue Luckily, both viruses required the full to be in a state of flux for some time version of Acrobat to execute. Those In the electronic publishing industry, until it arrives at a standard eBook file accessing PDF files using the free Ac- Microsoft has been pushing its own format. However, the fact remains that robat Reader (recently renamed “Adobe proprietary eBook file format based while PDF is one of the primary file Reader”) remained unaffected, as did on its Reader application. Microsoft formats in this industry and in mechani- those Mac OS X users of Preview. Ad- Reader has been squarely positioned cal design, it is not the only one, and ditionally, most antivirus products are against the PDF for secure / encrypted is universal only as long as competing now capable of scanning PDF files for eBook content ranging from best file formats stay below it. PDF is even known viruses. However, not everyone sellers to textbooks, and has virtu- being challenged in the web publishing uses antivirus protection of their com- ally displaced previous eBook file industry by Macromedia’s recent Flash- puters, though they should. As such, formats based on the Gemstar eBook Paper product. FlashPaper is designed the chance for similar events occurring file format. (Cesarini, 2002) Amazon to “convert any document into a Flash in the near future remains a possibility. now only sells eBooks in formats from file, that can be displayed in and printed Microsoft Reader and Adobe Reader from a browser window” in a manner The Competition (which uses a PDF specification em- purportedly faster and more accurately It could be argued that the continued ploying digital rights management for than PDF. (Becker, 2003) success of PDF depends on it being a commercial titles). monoculture. That is, since the whole Un-optimized for Computer point of the PDF hinges on its univer- The problem is two-fold: not only has Screen and Online Viewing sality, any threat to that diminishes Microsoft Reader reduced the value Usability expert Jakob Nielsen recently its potential for long-term usefulness. of PDF in the eBook industry, it is has voiced serious concerns over the use In a sense, this universality parallels rendered certain commercial eBook and apparent misuse of PDF online. Metcalfe’s Law: the value of a network titles platform-specific by default, In PDF: Unfit for Human Consump- increases exponentially with the num- since Reader is not available for Mac tion, Nielsen states that “Users get lost ber of nodes. In this case, the value of OS-based systems. This issue is inside PDF files, which are typically PDF as a universal document exchange compounded by a third eBook standard big, linear text blobs that are optimized format increases with the number of competing for market and mindshare, for print and unpleasant to read and people using it. Conversely, the value based on Palm Reader. Cora Nucci navigate online. PDF is good for print- decreases if people gradually stop using captured this problem well in E-Book ing, but that's it.” (Nielsen, 2003) it. Many companies are orchestrating Dilemma: Potboiler for the Digital Age. that precise scenario right now, and are Nucci states: Nielsen refers to numerous problems pushing their own respective file for- Imagine having to decide which CD associated with PDFs, including what mats as “the” file format for industry- player to buy based not only on fea- he refers to as a host of “usability specific universal document exchange. tures and price, but on what music crimes.” Nielsen argues that most you’d be able to play on it. Music PDF files are usually generated from Autodesk, for example, has actively labels would publish music in one or documents intended for hardcopy. As a campaigned for its Design Web Format more formats and pay commissions result, a great deal of PDF content on- (DWF) to displace PDF as the standard to the CD player manufacturers line does not follow typical guidelines for universal document exchange within based on the sales of each CD is- associated with online writing. These the architecture and mechanical design sued in its format. If you didn’t own files are usually too long, too static, and industries. Billing DWF as a “simple, the device(s) that supported discs in the words of Nielsen, often “unpleas- secure way to share design data,” Au- by your favorite artists, you’d be ant and boring to read.” todesk promotes the DWF files as being out of luck. This is pretty much how

5 Journal of Industrial Technology • Volume 21, Number 2 • April 2005 through June 2005 • www.nait.org

He also cites the “jarring user experi- document exchange by minimizing the pdfs/95003796_security_solbr_ue2. ence” when accessing PDF files online, Babylon of competing file formats. pdf since these files will either download Adobe. NA. (2003). Developer Solu- and open in a separate application, or However, it remains unclear if Acrobat tions – Legal Notices. Adobe.com. will launch within the web browser, will still be the default standard for Retrieved from Retrieved December but with PDF-specific toolbars, but- document exchange. The on-going 15, 2003, http://partners.adobe.com/ tons, and menu options. Nielsen argues push for increased XML integration asn/developer/legalnotices.jsp [Note: that “even when a PDF file has its own into the PDF standard is definitely a This is a password-protected site] navigation aides, they don't typically smart move, and can only help make Adobe. NA. (2003). Adobe Enter- help because they’re nonstandard and the PDF an even more widely diffused prise Solutions: The Adobe XML based on a paper metaphor rather than file format in a variety of industries. Architecture. Retrieved December hypertext navigation.” Simply put, PDF Yet, if challengers to the Acrobat 18, 2003, from http://www.adobe. files online do not behave similarly to monoculture succeed only partly, the com/enterprise/xml.html most other online content. Addition- “ripple effects” felt by these industries Angelo, M. (2003, November 21). ally, Nielsen stresses that online PDF could be substantial. Rather than being Openoffice 1.1 – A Complete Of- files break the flow of reading, since a universal document exchange format, fice Productivity Suite. Mozilla a separate application such as Adobe PDF could be relegated back to being Magazine. Retrieved December Reader or Preview must then launch, an industry-specific standard. Graphic 3, 2003, from http://www.mozil- and PDF layouts are usually optimized designers might use it, while mechani- laquest.com/ Linux03/OpenOf- for vertical, letter-sized paper, rather cal designers use something else, while fice_1-1_Overview_Story02. than the horizontal dimensions of most enterprise users rely on a different html#Microsoft-Formats desktop and laptop screens. Pivot standard, and web content producers Apple. (2004). Mac OS X – Architec- monitors aside, a great deal of scrolling rely on yet another. Secure, encrypted ture. Apple Computer. Retrieved must be done. eBooks may still be in a state of format September 29, 2004, from http:// flux, relying on a combination of PDF www.apple.com/macosx/architec- Regardless of whether one agrees or and other formats for commercial con- ture/ disagrees with Nielsen, he does bring tent. Even worse, standard file formats Autodesk. (2003). DWF vs. PDF. some challenging issues to light. may become not only industry-specific, Autodesk.com. Retrieved December However, these issues are not easily but platform-specific, as well. 18, 2003, from http://usa.autodesk. addressed. Fixing them would repre- com/adsk/servlet/index?siteID=1231 sent systemic changes to how Acrobat The road ahead for Adobe’s Acrobat 12&id=3523485 itself functions. Further, since the goal product line is unclear and beset with Becker, D. (2003, September 30). of PDF is to produce an exact replica of potential problems. If PDF is to remain Adobe’s PDF-everywhere Strategy. a file in a universal format, attempting a “positive monoculture” in docu- News.com. Retrieved November to somehow interpret the file differ- ment exchange, Adobe must continue 8, 2003, from http://news.com. ently for online use defeats the point of to broaden its appeal and increase its com/2008-1012-5083805.html creating a PDF. In view of this, Nielsen feature set and overall usability, yet Becker, D. (2003, September 18). suggests “gateway pages” are the not water it down so much that PDF Adobe e-doc format under siege. least bad solution. That is, rather than becomes the least worst solution, the News.com. Retrieved November directly linking to a PDF, he suggests lowest common denominator in docu- 8, 2003, from http://news.com. web designers instead create pages ment exchange. Otherwise, it would be com/2100-1012-5078712.html “that summarize the contents of big Babel all over again. Becker, D. (2003, November 10). documents and guide users gently into Adobe Buys XML Software maker. the PDF morass.” (Nielsen, 2003) References Retrieved November 12, 2003, from Adobe. NA. (2005). What is Adobe http://news.com.com/Adobe+buys+ Conclusion PDF? Adobe.com. Retrieved January XML+software+maker/2100-1012_ Five years from now, Adobe will still 16, 2005, http://www.adobe.com/ 3-5104919.html have numerous Acrobat products and products/acrobat/adobepdf.html Cesarini, P. (2002). eBooks: A Battle of the PDF will likely still be robust and Adobe. NA. (2004). Acrobat Elements. Standards. The Writing Instructor. widely-used. The strengths Cheng Adobe.com. Retrieved October 5, Retrieved July 12, 2004, from http:// highlights in the current version of 2004, http://www.adobe.com/prod- www.writinginstructor.com/essays/ Acrobat: simplicity and flexibility, will ucts/acrobatel/main.html cesarini/index.html likely continue to be strong selling Adobe. NA. (2004) Secure Electronic Cheng, W. (2002). Portable Document points. (Cheng, 2002, p. 63) Aside Documents Drive Efficient Business Format (PDF)–Finally, a Universal from versions of the product geared Processes. Adobe.com. Retrieved Document Exchange Technology. toward specific industries, the overall November 22, 2004, http://www. Journal of Technology Studies. goal will likely remain the same: ease adobe.com/products/server/ 28(1), 59 – 63.

6 Journal of Industrial Technology • Volume 21, Number 2 • April 2005 through June 2005 • www.nait.org

DuCharm, Robert. (1999). XML: The box/20030714.html Quigley, P. (2003, April 22). Adobe Annotated Speciﬁcation. Upper Nucci, C. (2001, February 5). E-Book Pulls XML into PDF Mix. Retrieved Saddle River, NJ: Prentice Hall. Dilemma: Potboiler for the Digi- June 6, 2003, from http://www. Evers, J. (2003, July 15). Adobe Pairs tal Age. TechWeb.com. Retrieved contentmanagement365.com/Con- PDF, XML. Retrieved July 30, 2003, July 22, 2002, from http://content/articles/article924.aspx from http://www.pcworld.com/news/ tent.techweb.com/wire/story/ Shankland, S. (2001, August 7). New article/0,aid,111577,00.asp TWB20010205S0002 Virus Travels in PDF Files. News. Hoffman, R. (2001). Resisting the Olavsrud, T. and Orzech, D. (2003, com. Retrieved December 22, 2003, Path of Least Resistance. Network July 15). Adobe Ties PDF Format to from http://news.com.com/2100- Computing. Retrieved September XML. Retrieved July 20, 2003, from 1001-271267.html?legacy=cnet 19, 2003, from http://www.net- http://www.cioupdate.com/news/ar- Symantec Antivirus Research Center. workcomputing.com/shared/print- ticle.php/2235401 (2003, May 2). W32.Yourde. SARC. Article.jhtml? article=/columnists/ Quan, M. (2000, September 28). com. Retrieved July 3, 2003, from 1208colhoffman.html&pub=nwc E-Books Face Standards, Copy http://securityresponse.symantec. Nielson, J. (2003). PDF: Unﬁt for Protection Issues. TecWeb.com. com/avcenter/venc/data/w32. Human Consumption. Useit. Retrieved November 14, 2002, from yourde.html com. Retrieved October 22, 2003, http://content.techweb.com/wire/ from http://www.useit.com/alert- story/TWB20000928S0004