DIGITAL OBSOLESCENCE 
Sandra Deljanin, University of Belgrade, Faculty of Philology, October 2011 
Summary 
Problems of digital obsolescence due to obsolescence of computers, software and data  mediums are presented in this article. 
Librarians and archivists are mostly concerned  because of the "digital dark age" phenomenon, and they are looking for more efficient  solutions to preserve cultural and intellectual heritage in digital form in order to decrease expenses and prevent time wasting. 
Further in the article, disadvantages of some  computer platforms and methods of temporary data revival are shown, but for now no  efficient standardized and long-term strategy, which could be applied to all types of digital resources, has been established. 
Many examples of computer, format, program and  medium obsolescence that are listed, should awake everyone's consciousness no matter  what their professional occupation is, because contemporary business and social life  can't be imagined without computer technology which makes communication easier  and faster, but it can also disable and interrupt all connections with future generations. 
Key words: digital obsolescence, Domesday project, emulators, format specifications, digital dark  age, digital preservation, digital preservation strategies.  
Introduction 
Situation in which digital resource cannot be  read anymore, either because physical medium  that contains it is no longer in use, or hardware  or software which executes it is not available, is  known as the digital obsolescence phenomenon.  
Common text can be presented on a stone plate,  on parchment or microfilm, and it will always  be recognized as written text. 
However, as soon  as the text is digital it presents only an electric  impulses flow and those impulses are meaningful only when they are interpreted by software  which created them or for which they were intended. 
Rapid evolution of technological innovations and spreading of various computer hardware, digital coding options, operational systems  and general or specific software are followed by  many serious problems which are questioning  digital preservation.  
Attention was brought to librarians and archivists in the 1990s. 
Experts in those branches  discussed this topic a lot, but without any significant solution except for continuous and immediate transfer of data and information to latest  media according to the current standards. 
Librarians were under pressure to use every innovation  right after its invention in order to keep up. 
If the  latest technology had failed, one of solutions out  of the situation was to transfer all resources to  newer digital media. 
Downside was money and  time wasting, which are always deficient, which  lead to resources being unavailable and libraries  becoming museums of failed technology. (Crawford and Gorman 1995) 
Digital media get worn out and damaged over  time. 
These changes needn't be obvious as it is  the case with photos or books, but they are present and almost everyone who owns a computer  experienced that - hard disk crashing, compact  disc scratching, bit rot on magnetic tapes, or  just breaking down of data reader. 
Even if data  remain intact and bites are still on media, it is  necessary to keep up with information about  which computer platform can read them and in  which format they are. 
It makes the data retrieval  process, with which librarians and archivists are  faced with always growing data collections, even  harder. 
There is a known case of NASA (National  Aeronautics and Space Administration) space recordings and pilotless spacecrafts Viking 1 and  Viking 2 landing on Mars in 1976 saved on magnetic tapes. 
When the recordings were to be analyzed they turned out to be unreadable because  they were in unknown format and their creators  had meanwhile passed away or left NASA.  
The recordings were eventually extracted after  months of resolving doubts through thorough research about how recording machines had functioned. (Blakeslee 1990) 
2. BBC Domesday Project 
One of the most famous examples of digital  data loss due to digital obsolescence is the BBC  Domesday Project, in which the entire British nation took part and whose research was compiled  nine hundred years after the Domesday Book had  been published. 
Original document known as the  "Doomsday Book" presents census of eleventh  century England started in 1086, ordered by King  William the Conqueror. 
TV producer from BBC  Peter Armstrong started an interesting adventure  of reviving these traditional data collections with  new additions, photos, precise locations, town  descriptions and reports from people across the  country about everyday topics in 1983. 
He gathered leading minds in technology and started one  of the main interactive projects of the time. 
This multimedia publication in which over  million people took part was published in 1986.  
More than 2 GB of data were gathered, which  was a stunning amount for that time and the  most common way for transferring data among  computers were 5.25" floppy discs. 
Considering  their limited capacity of 1.2 MB, results of the  project were finally put on adopted laser discs,  CD-ROM ancestors, in LV-ROM format (Laser  Vision Read-Only Memory). 
Two discs, Community Disc and National Disc were in the size of  a gramophone record (12") but they looked like  compact discs we use today with 300 MB of storage space on each side of the disc. 
They were  readable by a specially configured player philips  VP415 called the Domesday Player, on Acorn  computer BBC Master increased by SCSI controller (Small Computer System Interface). 
User  interface consisted of BBC Master Keyboard and  trackerball by which the user could move cursor  on a screen and choose action with a click. 
Software for the project was written in BCPL (Basic  Combined Programming Language) which was  not widely spread and can be considered a C language ancestor. (Darlington et al. 2003) 
Several libraries bought the whole system  package, but it was far from the original idea of  wide distribution. 
Participants of the project were  disappointed because their hard work wasn't easily available in public. 
As time went by this project became a basic example of digital obsolescence, because less and less machines had access  to it. 
While information from the book are available nowadays, Domesday project discs with  "more than 250.000 place names, 25.000 maps,  50.000 pictures, 3.000 data sets, 60 minutes of  moving pictures" (McKie and Thorpe 2002)  have become unreadable due to small ability of  contemporary computers to read old formats and  the ability to access laser discs is even smaller.  
A group of researchers from Michigan and  Leeds Universities formed the CAMiLEON  consortium (Creative Archiving at Michigan  &   Leeds: Emulating the Old on the New) in 1999,  in order to save data from Domesday discs. 
In 2003 CAMiLEON successfully improved the  system. 
They enabled access to discs that were  already in bad physical shape by original hardware emulator. 
During the process, CAMiLEON  was researching and developing strategies to  preserve digital material, so this project was an  important testing ground for implementation of  new strategies and development of the software  emulating program. 
Another team which worked  for The National Archives of Great Britain (The  National Archives in Kew) traced the original 1"  magnetic tape. 
It contained photos and maps of  Great Britain with locations of all important data  that were used for the discs. 
Photos and maps  have been scanned and laser discs converted into  new digital format which can be read on different  machines. 
In July of 2004 data were published  on the web but this version was removed from  the web in 2008 when its author Adrian Pearce  died. 
BBC Learning team led by George Auckland  published large amount of data from the Community Disc again in 2011 in format available  on the web named Domesday Reloaded (http:// www.bbc.co.uk/history/domesday). 
On this internet site, one can access photos and articles  from the original project and see how life of British people has been changing in the last 25 years,  while visitors can refresh information with their  memories, photos and stories. 
3. Types of obsolescence 
Massive use of DVDs instead of video cassettes, or use of USB memory for data transfer  instead of floppy disc, presents only few of many  examples of technical obsolescence where new  technology replaces the old one, becomes preferred and starts to be used more than the old  one. 
Single products can be overtaken due to inability of technology to proceed with its production. 
It mostly happens when it is pushed from  market either because its creator left business or  it was bought by competitor which intentionally  kills all his products. 
Some products become functionally obsolete  when they don't work anymore in the way they  used to when they were created, either because of  inevitable natural wear or because of some intervening act. 
Product can be intentionally designed  to use components that get worn out faster, which  leads to planned obsolescence. 
Example for this  type of obsolescence is producing some appliance designed to wear within five years from  the shopping day, forcing customers to replace it  with new after that amount of time. 
Planned systemic obsolescence is intentional attempt to make product obsolete by  changing its functional system in such a way  that it makes its use harder. 
New software  which is being introduced is often incompatible with older versions. 
Although, for example, older version of the word processing program is working well, it is mostly not  able to read data saved in new version. 
Lack  of compatibility is forcing users to buy new  programs although the old programs are still  working correctly. 
The other way to introduce  systemic obsolescence is by eliminating maintenance services. 
If the product breaks down,  user is forced to buy a new one. 
The only, but  very important case where this example of systemic obsolescence can function is proprietary  software which is licensed by exclusive copyrights, where the third party is not allowed to  intervene on the product. 
Well known example  of this is when microsoft stops their customer  support for older versions of windows and  older service packages on new versions, like  disabling web browser Explorer 9 within operating system windows XP. 
Postponement obsolescence is a situation in  which technological improvement of product is  not introduced even if it is possible, when manufacturer is not able or doesn't want to sell some  software service, but they enable users to install  software on computer and use it for limited time. 
In the meantime, users can decide if they want  to buy replacement, to upgrade it or to start using newer software. 
In some cases old technologies are used deliberately in order to avoid data  intrusion, a strategy known as "security through  obsolescence". 
4. Emulation of obsolete computers 
Computer hardware becomes obsolete when  new generations of processors with increased capabilities replace the existing ones. 
Progress from  large and expensive computers with calculating  abilities to contemporary, powerful, cheap, fast  and reliable computers in different sizes and features lasts less than an average human lifetime.  
The fact that computers which are available today will be outdated in five years is devastating.  
Some manufacturers stopped producing and their  computers have automatically become obsolete,  like TI-99, Commodore 64 and Amiga. 
On the  other hand, new computer hardware opens doors  to new and improved programs, thus directly influencing software and format obsolescence. 
Thanks to the invention of hardware device  i.e. software, the so called emulator, whose role  is to imitate some other system that is not available, nowadays we can count on preservation of  electronic data saved on media dependant on specific computer constructions, providing that special care is given to preserving media for storage  for longer periods. 
Emulation is not focused on  the digital object but on systematic surrounding  in which the object is shown and from which it  originates. (Van der Hoeven, et al. 2007) 
Through  emulation, functions of a system are reproduced  in such a way that they can be activated in some  other totally different system which is going to  act and look like the original system.  
Imitation or "emulation is a special type of  software application that creates a virtual object  computer on a currently available host computer... 
Frequently, the object computer hardware is  not available at the time the software engineers  begin programming for it. Virtual hardware, or  emulation, is commonly used to substitute for the  unavailable object computer hardware to allow  both engineering tasks to be developed simultaneously... 
Although emulation is most commonly used to emulate future hardware designs,  it is also used - and arguably more easily - to  create virtual historic or obsolete computers."  (Quick, Maxwell 2005) 
Their precious software  is executed on modern computers thanks to emulators which can be found on websites like http:// www.amigaforever.com and http://www.c64.com. 
"There is no comercial computer which hasn't  been emulated in some way, from first personal  computers like Commodore PET, or Apple II  to contemporary Pentium PCs and Power Mac  computers. 
Some of obvious reasons for emulator popularity are nostalgy, playing old games,  need for software which doesn't exist on modern  machines, and even education." (Ćalić 1998) 
5. Storage media temporariness 
Just as the advance of technology led to the  computer hardware obsolescence phenomenon, a  similar situation is present at data storage media  which are leaving space for their faster, smaller,  with larger capacity and easier to read heiresses.  
"Frequently the new hardware is not backward  compatible with the older hardware's media for  more than one generation." (Quick, Maxwell  2005) 
That is the case with device for the 3.5"  floppy discs which haven't gone out of use completely, but this device is not being built in the  new generation computers even though it used  to be a part of standard equipment. 
Floppy disc  used to be the main transferring medium between  computers until the appearance of CDs and other  advanced relatives, and today only its icon is in  wide use as a metaphor for data storage on the  interface of most types of software (e. g. option  Save within microsoft Office package). 
It's a fact that bits on media get lost in time.  
One of the reasons for that outcome is physical  features of materials the media are made from,  which have variable characteristics that make  them unstable. 
"Nature tries to equalize energy  levels, and over time, it succeeds at erasing the  data that is stored on most digital media. 
To store  data for a long time, the media the data is stored  on must be nearly entropically equalized to start  with so that further deterioration will take centuries to happen." (Quick, Maxwell 2005) 
All magnetic mediums have high entropical energy, and  only few optical media are close to be entropically equalized.  
There are many commercial firms that offer  media migration, format conversion and data  recovery services and expenses vary depending  on procedure difficulty. 
"Simple migration of  standard format 5.25" disks can cost anywhere  from $5-$50 per disk and up", data conversion  increases the price of service while restoring data  from damaged media costs even more. (Entlich  2004) 
"Even if data migration is flawless across  intermediate media with repeated reading and  writing using differing technologies, the time  spent idle between migrations will take its toll  on the stored data bits. 
Data migration success  rates are never 100% and successive storage/ migration cycles accumulate failures and expose  the data to corruption and loss." (Quick, Maxwell 2005) 
Besides data preservation on media  problems, there is a problem of reading media on  which data are still present but are coded because  decoding process is being deliberately hardened.  
Modern encryption is being more and more used  in documents and media because publishers want  to protect their copyrights by limiting usage of  digital content and by method of DRM (Digital  Rights Management). 
Paul Conway pointed out that "as our capacity to record information has increased exponentially over time, the longevity of the media used  to store the information has decreased equivalently." (Li, Banach 2011) 
Although all digital  media are susceptible to the obsolescence phenomenon, the ones more equalized with standard  and in wider use will obsolete slower. 
"When  selecting a storage medium for digital materials,  it's important to choose a type and brand that has  a reputation for good quality. 
While all media  will fail eventually, higher-quality media will  last longer and ultimately help reduce the cost of  replacing media over time." (Bailey 2011) 
Also,  making backup copies on different media will  decrease possibility of valuable digital data loss.  
"To avoid storage hardware dependence, the  storage media must not be tied to any one manufacturer and the retrieval device must be able to  be crafted from simple parts. 
Future generations  must be able to construct a device to read the media with minimal understanding of what is on the  media and with simple, readily available parts."  (Quick, Maxwell 2005) 
6. Classification and cataloging data format 
Although some format specifications are independent from specific software like coding  ASCII and Unicode schemes, most of them are  connected to related software groups. 
Software  and format specifications on which it is based  usually develop together and therefore are necessarily in tight connection. 
This is why discussions about format obsolescence must include  software obsolescence issues. 
Usually efficient  software is being upgraded. 
Although most applications can read files created by previous  versions, or the one before, ability to read even  older versions mainly doesn't exist. 
The latest  versions of software most often can't read files  which haven't migrated, while older versions of  software often are not available or can't be run  on current computer or under current version of  operating system.  
The most problematic formats are those formats whose specifications are proprietary and  closed and which are being connected to efficient  long lasting software. 
They have a tendency to  grow fast and exist in many different versions for  different platforms, and their compatibility with  older versions is limited. 
Manufacturers follow  commercial moment deliberately avoiding compatibility with older versions of their own software in order to force all users, including the ones  who prefer older versions, to do upgrading. 
To  make it work, attention of users is being held by  attractive offers of additional functional applications, ensuring constant incomes. 
These formats  are the most endangered ones because they face  fast specification change on one side and depending on one product or company on the other. 
Formats that are proprietary and open pose  less risk of obsolescence because specifications  are available in public allowing other companies  to produce software which can read them. 
An example is a subset of proprietary format which  was adopted as standard PDF/A, archive version  of PDF owned by Adobe but is an open specification. 
PDF/A differs from PDF in that it requires  XML format based metadata as well as removal  of distracting elements which would complicate  decoding and speed up obsolescence - like audio  and video recording, JavaScript etc. 
This kind  of specifications is still susceptible to market  forces' caprices and can easily be abandoned for  commercial reasons.  
It can be said that specifications that are nonproprietary and open are the most secure for  data storage. 
They are supported by international  standards bodies whose representatives help  equalizing needs of a variety of users who are  not reflection of any single commercial interest in standard creating. 
Open formats are also  called free file formats unless they are bound by  copyrights, patents or other limitations, so everyone can use them for any purposes without  charge. 
Compatibility with old versions is priority of these standards so there are no commercial  pressures for rapid obsolescence.  
Until today, thousands of formats and their  versions have been created and only recently an  effort has been made to catalogue and document  them and understand their relations and variations. 
Without appropriate software file format  documentation and specifications, attempt to interpret old file or even to determinate in which  format it was written becomes scary. 
Digital  protection department of the Great Britain National Archive has developed an online information system about file formats and their following software products, PRONOM. 
Originally it  was developed as support for access to electronic  data records of the National Archive and for long  termed preservation, and today it is available for  every single person who needs information about  software products, their support and technical  requirements life cycle and about formats supported by some diferent software.  
Many projects involved with preservation of  cultural heritage are facing inevitable questions  about digitalization - "how to digitalize, in which  format, how detailed...?". 
NINCH (The National  Initiative for a Networked Cultural Heritage),  situated in Washington USA, lists the following  formats as de facto standards which probably  won't obsolete in close future: uncompressed  TIFF and PDF for images, ASCII and RTF for  text. (2002) 
Systems dependant on copyright  types of software whose license conditions and  software existence are not long-termed are not  appropriate for archiving and for making digital  collections of cultural heritage.  
File formats in which data are saved should  be used widely, compatible with previous versions with history of compatibility available,  have reasonable upgrading cycles, solid support  to metadata, built-in error checking, open, uncompressed or to use compression without loss,  and finally work with wide specter of hardware  and software configuration. (Bailey 2011) 
7. Is it possible to escape from "digital dark age" and how? 
While it is still possible to read our written  heritage that is more than hundreds of years old  on analog media, digital data that are only a few  years old are in serious danger of being lost forever. 
An attempt to switch all digital media into  analog form is almost mission impossible, even if  the fact that it would take eternity is disregarded.  
Solid copies are more resistant to obsolescence,  but they can't reflect the real nature of multimedial digital forms and by no means are they able  to replace them. 
Suggestions to form digital museums in which old machines that can run original software and compatible obsolete formats  would be kept also have no grounds. 
Maintenance expenses would be high, access to original  digital documents would be possible in only few  locations in the world and as already stated, computer hardware has limited lifetime. 
"The rate of  digital obsolescence keeps accelerating, and the  serious search for a long-term strategy for storage has yet to begin." (Brand 1990) 
The main challenge digital generation is faced  with is: "how can masses of machine-generated,  machine-readable material be stored in a form  that is safe, secure from degradation and - potentially most calamitous in the long term - accessible to subsequent generations?" (Huxley 2005)  
There have been many tactics for protection of  digital data which can be successfully performed  by persons and organizations on specific types  of materials in specific surroundings. 
However,  none of them is suitable for all types of data, neither efficient in all situations nor adequate for all  institutions responsible for preserving cultural  heritage. 
Variety of formats and specifications additionally make finding a unique solution harder.  
Appropriate strategy should be determined by the  type of digital object which is to be preserved, by  requests of users who want to access the object,  and by politics of institutions that are responsible  for preservation of digital sources.  
Digital preservation is active managing of  digital information through a wide specter of  activities which will ensure their availability,  increase their lifetime and protect them from  being ruined, from physical damaging and obsolescence. 
This is a dynamic and continuous  process during which methods and technical requirements change along with rapid technological changes and which is followed by constant  investing of effort, time and money. 
Long-term  storage of information without error in proper  formats and on long life media makes it possible  to retrieve data in their original form, so a human  can read and understand them but they can also  be processed by a computer. 
"The "digital dark  age", in other words, could yet become a digital golden age, with the total of human knowledge preserved for and accessible to everyone."  (Colvile 2007) 
7.1 Digital preservation strategies 
1. Bitstream copying - strategy also known  as backing up data is a process of making an identical copy of a digital object.  
Though a necessary component of all  strategies for digital preservation, it is not  a long lasting technique by itself because  it deals only with data losses caused by  hardware and media failure, whether it is  normal malfunction and decay or system  failure, malicious destruction or natural  disaster. 
Bitstream copying is often combined with remote storage and saving  copies on different locations in order to  avoid the possibility that both the original and the copy are subjects of the same  disaster. 
2. Refreshing - this is a process of copying  digital information from one long-term  storage medium to another of the same  type without any changes in bitstream  (for example from older CD-RW to newer CD-RW). 
Modified refreshing is about  copying data to another medium of similar  type without changes in bit-pattern (from  100 MB Zip disk to 750 MB Zip disk).  
Durable media like Gold CDs can lessen  the need for often refreshing and decrease  losses due to medium weariness, but durable media don't have infinite influence  on any potential loss source - they only  give false sense of security. 
3. Technology preservation - is based on  preservation of technical surrounding in  which a system is run, including operative  systems, original application software,  appliances and so on. 
Sometimes this option is called computer museum. 
It offers  possibility to face medium obsolescence  providing that medium is not broken so  it can't be read anymore. 
This is not a  strategy which can be run by a single institution because maintenance of obsolete  technology requires significant investments in equipment and staff. 
4. Digital archeology - includes methods  and procedures of rescuing content from  damaged media or from obsolete or damaged hardware and software environment.  
Digital archeology is explicit strategy for  urgent recovery of bitstream from unreadable medium whether due to physical  damage or hardware failure. 
Readable bitstreams can often be retrieved even from  very damaged media (especially magnetic  media), but if content is very old, there is  a high possibility that retrieving may not  be possible and that content will not be  understandable.  
5. Analog backups - involves conversion  of digital objects into analog form according to archive standard and using  durable analog media like microfilms for  preservation in archive conditions. 
To this  type of transfer most reliable are text and  monochromatic photos because the loss  of functionality of the original document  is minimal. 
Considering high costs and  limitations of creating analog backing up  copies, this technique makes sense only  for documents whose content deserves  highest level of loss protection. 
6. Migration - involves transferring data  into new systematic environment, conversion from one format into another, from  one operative system into another, from  one program language into another, from  one computer technology generation into  next generation, while old data remain  unchanged. 
According to some, migration is used interchangeably with refreshing but it is a broader and richer concept  than refreshing. 
Purpose of migration is  to preserve integrity of digital objects so  clients would be able to use them in the  face of constantly changing technology.  
Some criticized this method claiming that  it can offer neither integrity nor authenticity - there is always danger to lose during  this process partial functionality which  existed in old format, or that convertor  itself won't be able to encode or transfer  all features of original format (especially  when it comes to data protected by copyright). 
7. Reliance on standards - this method is  based on adhering to stable, broad accepted and well-recognized open standards during creating and archiving digital sources. 
This kind of standards are not  related to specific hardware or software  platform and in that way they can delay  inaccessibility of digital resources due  to technological obsolescence. 
However,  stable standards are not available for all  types of formats. 
8. Normalization - is a formalized implementation of reliance on standards. 
Within  an archival repository all digital objects of  specific type (e. g. color photos) are being  converted into one chosen file format (e.  g. TIFF) which will reflect compromise  among many features like functionality,  durability and preservability. 
By normalization of stored objects into set of chosen  formats whenever it is possible, number  of formats is controlled and complexity of  file managing is decreased. 
9. Canonicalization - technique designed to  enable determination whether important  document characteristics have remained  unchanged through conversion from one  format into another. 
It relies on creating  representative type of digital object which  conveys which are the key aspects of digital object. 
Once created, this form or pattern can be used to algorithmically test if  converted file has lost any of its essence. 
10. Emulation - combines software and  hardware to reproduce running of another  computer with all its main characteristics,  allowing programs or media designed for  certain environment to be executed in different, most often newer environments.  
Emulation requires creating of emulators, programs for transferring code and  instructions from one computer environment so it can be properly executed in  another. 
Well known use of emulators is  at newer version of Apple Macintosh operating system, which enables use of programs based on previous series of processors no longer used on Apple computers.  
Most of emulators available today were  written for computer games of obsolete  hardware in order to run them on modern  computers. 
11. Encapsulation - technique of grouping  digital objects and metadata to provide  access to the object. 
Grouping process  should decrease the possibility of losing  any key component vital for decoding and  presenting of the digital object. 
Appropriate types of metadata hermetically closed  with the digital object include: reference (it  provides one or more markers for unique  identification of objects), representation  of information (provides interpreting bits  in appropriate way), provenance (description of object source), fixity (proof that  object is intact), and context information  (describes how object is related to other  information outside logical structures  called "containers" or "shelves"). 
It is  considered to be a key element of emulation.  
8 Conclusion 
It is very important to be aware of use and  limits of different digital forms, which should  meet not only temporary purposes but also to be  functional and available in the future. 
Not many  people think about the fact that almost all of our  knowledge recorded in digital form cannot last  even for our lifetimes. 
"To those who believe in  the immortality of new media files, Rothenberg  offers a suitably new-age adage: Digital information lasts forever - or five years, whichever comes  first." (Huxley 2005)  
Since microfilm proved to be one of the most  durable media for data storage in analog form  (it can remain intact more than five hundred  years), some started thinking in that direction  to store digital data on this medium. 
Company  which deals with services in the area of information technologies, ACS (Affiliated Computer  Services), applied a request in 2004 for patenting technology of archiving binary data, Method  and apparatus for preserving binary data. (PatentGenius) 
In order to place binary data on microfilm, it is necessary to present them as images  readable by machines. 
Creators of this invention  suggested use of 2-D barcode symbols for encoding binary data, whose symbols join into images  readable by microfilm writer device. 
Also, "any  available microfilm scanner that can capture a  clear image of the 2-D barcode symbol on the  microfilm can return the image to a digital image in a computer." (Quick, Maxwell 2005) 
Correctly defined specification for encoding can be  stored together with binary data in order to make  easier later recovery of data even if techniques  for coding become obsolete. (PatentGenius) 
As far as it is known, this method for data  storage hasn't still found its broad use but it certainly implies possibility to come up with some  new techniques which will face key problems of  digital preservation, no matter how unpopular  they are at the moment. 
