Weekly readings - 13 October 2006

What Is Needed to Educate Future Digital Librarians. Youngok Choi, Edie Rasmussen. D-Lib Magazine. September 2006.

Educating digital librarians has become an important agenda item. The role of libraries has changed with the new digital environment. Educational programs need to be created to prepare future digital librarians for libraries. Some of the new roles include positions similar to Digital Initiatives Librarian, Metadata Librarian, Digital Preservation Librarian, Digital Imaging Specialist, Digital Technologies Development Librarian, and others. New skills identified fall into areas such as Technology, Library related skills, and others, such as communication and interpersonal skills, project management, presentation, and grant writing. Findings include:

·Digital libraries are collaborative in areas from computing systems to traditional library functions.

·Digital library jobs will be very attractive to the next generation of library professionals

·Major tasks include management, leadership, and website-related tasks. Monitoring the practice and standards of current digital libraries, is critical.

·Soft skills, such as communication and project management are needed in digital librarianship. Digital librarians must adapt to change and continue to learn.

·Education programs must emphasize skills and competencies and technical and information skills.

Skype's Venice Project Revealed. Steve Rosenbush. BusinessWeek. October 5, 2006.

Skype is unveiling its latest product, a web site that combines TV and video with the interactive tools of the internet. The site should be available by the end of the year. They are trying to convince media and TV companies to place their full-length content on the network, but adding content will also be open to anyone. The site is designed to work within the intellectual property rights system. It is based on peer-to-peer technology, in which the infrastructure comprises user PCs, not central servers. The videos are streamed to the computers, not downloaded.

Moving towards shareable metadata. Sarah L. Shreeves, Jenn Riley, and Liz Milewicz. First Monday. August 2006.

Shareable metadata is metadata which can be understood and used outside of its local environment by aggregators to provide more advanced services. Sharing metadata and the resultant aggregations benefit users, particularly those users whose subject interest cuts across disciplinary boundaries. Aggregations also benefit the institutions sharing the metadata. Institutions can no longer assume that users know about their online collections and remember to visit them. By allowing their metadata to appear in places outside of the original collection, institutions increase the number of access points to the items in their collection and expose their collection to a broader audience. Problems include:

·Inconsistency within a single collection.

·Too much information.

·Lack of key contextual information.

·Lack of conformance to technical standards.

Shareable metadata is different from in house metadata; it should be human understandable, and quality data, thought that does not mean complex. The following characteristics are particularly important:

·Content is optimized for sharing.

·Metadata within shared collections reflects consistent practices.

·Metadata is coherent.

·Context is provided.

·The metadata provider communicates with aggregators through direct or indirect means.

·Metadata and sharing mechanisms conform to standards.

At the most basic level, institutions who contribute metadata through whatever means should consider the content and consistency of their metadata. Implementing shareable metadata may be a slow process that is conducted as institutions work with new collections, but the ability to think critically about the shareability of ones’ own metadata and the commitment to make the necessary changes will be key for the next stage of effective digital library services.

Arius3D Canada Inc.: University College London, Petrie Museum to Digitize Collection. News Release. Oct. 5, 2006.

Arius3D provides digital archiving solutions. It is the only three-dimensional measurement system that simultaneously captures color and geometry from real world objects. It is affected by ambient light, so it provides an accurate and precise image. Once an object's image is captured it can be redeployed in a multitude of resolutions and in a range of file formats.

Weekly readings - 13 October 2006

What Is Needed to Educate Future Digital Librarians. Youngok Choi, Edie Rasmussen. D-Lib Magazine. September 2006.

Educating digital librarians has become an important agenda item. The role of libraries has changed with the new digital environment. Educational programs need to be created to prepare future digital librarians for libraries. Some of the new roles include positions similar to Digital Initiatives Librarian, Metadata Librarian, Digital Preservation Librarian, Digital Imaging Specialist, Digital Technologies Development Librarian, and others. New skills identified fall into areas such as Technology, Library related skills, and others, such as communication and interpersonal skills, project management, presentation, and grant writing. Findings include:

·Digital libraries are collaborative in areas from computing systems to traditional library functions.

·Digital library jobs will be very attractive to the next generation of library professionals

·Major tasks include management, leadership, and website-related tasks. Monitoring the practice and standards of current digital libraries, is critical.

·Soft skills, such as communication and project management are needed in digital librarianship. Digital librarians must adapt to change and continue to learn.

·Education programs must emphasize skills and competencies and technical and information skills.

Skype's Venice Project Revealed. Steve Rosenbush. BusinessWeek. October 5, 2006.

Skype is unveiling its latest product, a web site that combines TV and video with the interactive tools of the internet. The site should be available by the end of the year. They are trying to convince media and TV companies to place their full-length content on the network, but adding content will also be open to anyone. The site is designed to work within the intellectual property rights system. It is based on peer-to-peer technology, in which the infrastructure comprises user PCs, not central servers. The videos are streamed to the computers, not downloaded.

Moving towards shareable metadata. Sarah L. Shreeves, Jenn Riley, and Liz Milewicz. First Monday. August 2006.

Shareable metadata is metadata which can be understood and used outside of its local environment by aggregators to provide more advanced services. Sharing metadata and the resultant aggregations benefit users, particularly those users whose subject interest cuts across disciplinary boundaries. Aggregations also benefit the institutions sharing the metadata. Institutions can no longer assume that users know about their online collections and remember to visit them. By allowing their metadata to appear in places outside of the original collection, institutions increase the number of access points to the items in their collection and expose their collection to a broader audience. Problems include:

·Inconsistency within a single collection.

·Too much information.

·Lack of key contextual information.

·Lack of conformance to technical standards.

Shareable metadata is different from in house metadata; it should be human understandable, and quality data, thought that does not mean complex. The following characteristics are particularly important:

·Content is optimized for sharing.

·Metadata within shared collections reflects consistent practices.

·Metadata is coherent.

·Context is provided.

·The metadata provider communicates with aggregators through direct or indirect means.

·Metadata and sharing mechanisms conform to standards.

At the most basic level, institutions who contribute metadata through whatever means should consider the content and consistency of their metadata. Implementing shareable metadata may be a slow process that is conducted as institutions work with new collections, but the ability to think critically about the shareability of ones’ own metadata and the commitment to make the necessary changes will be key for the next stage of effective digital library services.

Arius3D Canada Inc.: University College London, Petrie Museum to Digitize Collection. News Release. Oct. 5, 2006.

Arius3D provides digital archiving solutions. It is the only three-dimensional measurement system that simultaneously captures color and geometry from real world objects. It is affected by ambient light, so it provides an accurate and precise image. Once an object's image is captured it can be redeployed in a multitude of resolutions and in a range of file formats.

Weekly readings - 6 October 2006

Fedora and the Preservation of University Records Project. Eliot Wilczek, Kevin Glick. Project web site. September 2006.

This project examines electronic records preservation research and theory with digital library practice. The three areas looked at are:

1. Requirements for trustworthy recordkeeping systems and preservation activities,

2. Ingesting records into a preservation system, and

3. Maintaining records in a preservation system.

The project provides twelve reports and an ingest prototype tool. The sections include:

1. Introduction: Overview, model, concerns

2. Ingest: Ingest guide, projects, tools

3. Maintain: Guide, checklist

4. Findings: Analysis of Fedora’s ability to support preservation activities, conclusions, future directions

A few notes from the conclusion that caught my interest:

· The OAIS Reference Model is the overarching conceptual structure for preservation activities and systems.

· The Ingest Guide and Maintain Guide translate the requirements into actions in those areas

· Long-term preservation of archival university records is a difficult and costly endeavor.

· Because of resource costs, most archives must develop partnerships to successfully preserve electronic records and digital objects.

· Archivists must become a step removed from the records they manage if they are going to preserve them.

· Archivists must work with record creators as they create their records to preserve them

CEATEC: Hitachi Maxell develops wafer-thin storage disc. Martyn Williams. Computerworld. October 04, 2006.

The stacked volumetric optical disc (SVOD) is less than a tenth of a millimeter thick, and this thinness could give the technology an advantage over current CDs, DVDs and blue-laser discs, all of which are 1.2 mm thick. Many of the discs can be stacked together to realize a large data storage capacity in a small space.

New DVD could end format war. CNN. September 27, 2006.

New Medium Enterprises said it can produce a multiple-layer DVD disk containing one film in different, competing formats, such as Blu-Ray and HD-DVD.

This follows a patent by three employees at Warner Bros. in which these are complementary patents. By being able to put the same material on a single disk in the two competing formats this will resolve consumer’s concerns. The first prototype using the technology should be ready by early 2007. NME has also created the technology for the machines to read and write the disk. The technology can create DVD disks with up to 10 different layers that were still readable. Data on a DVD are stored at different depths depending on the technology: Blu-Ray discs store information 0.1 millimeter from the surface while HD-DVD discs store it at 0.6 millimeters.

With technology, records seem made to be forgotten. Charles Piller. Los Angeles Times. Sept. 18, 2006.

An article discussing the loss of digital items. It affects households as well as archivists. There is no list of lost records, but archivists continue to find examples. "If we don't solve the problem, our time will not become part of the past. It will largely vanish." Archivists expect that the current presidential administration records will be less complete than those of Lincoln. NARA is creating a system to preserve information, but some feel that each migration of data will lose some meaning. In other ways, each new migration generates more data which increases the complexity of the problem.

New 1TB Desktop External HD Goes for $500. Chris Preimesberger. eWeek. October 2, 2006.

Buffalo Technology has announced a new external hard drive which ranges from 500GB to 1.5TB. It has two drives that can be set up in a RAID-1 configuration for reliability. It is intended to make storage simple for end users. It comes with data encryption technology to prevent unauthorized access. The cost is $249 for 500GB up to $999 for 1.5TB.

Old E-Mail Keeps Getting More Expensive. Kim Nash. eWeek. September 26, 2006.

We all know it is expensive to go through old files and backup tapes looking for emails that are required for lawsuits or audits. Sometimes the cost of producing the files can be shared. But in a recent case, the judge ruled they: “should have reasonably anticipated having to produce all the former employees’ e-mails, and therefore kept that data in a form that was quick and easy to access – i.e. not archived on backup tapes stored offsite.”

Weekly readings - 6 October 2006

Fedora and the Preservation of University Records Project. Eliot Wilczek, Kevin Glick. Project web site. September 2006.

This project examines electronic records preservation research and theory with digital library practice. The three areas looked at are:

1. Requirements for trustworthy recordkeeping systems and preservation activities,

2. Ingesting records into a preservation system, and

3. Maintaining records in a preservation system.

The project provides twelve reports and an ingest prototype tool. The sections include:

1. Introduction: Overview, model, concerns

2. Ingest: Ingest guide, projects, tools

3. Maintain: Guide, checklist

4. Findings: Analysis of Fedora’s ability to support preservation activities, conclusions, future directions

A few notes from the conclusion that caught my interest:

· The OAIS Reference Model is the overarching conceptual structure for preservation activities and systems.

· The Ingest Guide and Maintain Guide translate the requirements into actions in those areas

· Long-term preservation of archival university records is a difficult and costly endeavor.

· Because of resource costs, most archives must develop partnerships to successfully preserve electronic records and digital objects.

· Archivists must become a step removed from the records they manage if they are going to preserve them.

· Archivists must work with record creators as they create their records to preserve them

CEATEC: Hitachi Maxell develops wafer-thin storage disc. Martyn Williams. Computerworld. October 04, 2006.

The stacked volumetric optical disc (SVOD) is less than a tenth of a millimeter thick, and this thinness could give the technology an advantage over current CDs, DVDs and blue-laser discs, all of which are 1.2 mm thick. Many of the discs can be stacked together to realize a large data storage capacity in a small space.

New DVD could end format war. CNN. September 27, 2006.

New Medium Enterprises said it can produce a multiple-layer DVD disk containing one film in different, competing formats, such as Blu-Ray and HD-DVD.

This follows a patent by three employees at Warner Bros. in which these are complementary patents. By being able to put the same material on a single disk in the two competing formats this will resolve consumer’s concerns. The first prototype using the technology should be ready by early 2007. NME has also created the technology for the machines to read and write the disk. The technology can create DVD disks with up to 10 different layers that were still readable. Data on a DVD are stored at different depths depending on the technology: Blu-Ray discs store information 0.1 millimeter from the surface while HD-DVD discs store it at 0.6 millimeters.

With technology, records seem made to be forgotten. Charles Piller. Los Angeles Times. Sept. 18, 2006.

An article discussing the loss of digital items. It affects households as well as archivists. There is no list of lost records, but archivists continue to find examples. "If we don't solve the problem, our time will not become part of the past. It will largely vanish." Archivists expect that the current presidential administration records will be less complete than those of Lincoln. NARA is creating a system to preserve information, but some feel that each migration of data will lose some meaning. In other ways, each new migration generates more data which increases the complexity of the problem.

New 1TB Desktop External HD Goes for $500. Chris Preimesberger. eWeek. October 2, 2006.

Buffalo Technology has announced a new external hard drive which ranges from 500GB to 1.5TB. It has two drives that can be set up in a RAID-1 configuration for reliability. It is intended to make storage simple for end users. It comes with data encryption technology to prevent unauthorized access. The cost is $249 for 500GB up to $999 for 1.5TB.

Old E-Mail Keeps Getting More Expensive. Kim Nash. eWeek. September 26, 2006.

We all know it is expensive to go through old files and backup tapes looking for emails that are required for lawsuits or audits. Sometimes the cost of producing the files can be shared. But in a recent case, the judge ruled they: “should have reasonably anticipated having to produce all the former employees’ e-mails, and therefore kept that data in a form that was quick and easy to access – i.e. not archived on backup tapes stored offsite.”

Weekly readings - 29 September 2006

Imaging technology restores 700-year-old sacred Hindu text. Physics.org. September 19, 2006.

Imaging techniques are being used to preserve an ancient Hindu text that is deteriorating due to age and improper storage and handling. The images are then being processed and stitched together. This will make opening the fragile book unnecessary in the future. The images are being stored electronically, in printed form, and etched on silicon wafers.

Brother, Can You Spare a Terabyte? Jennifer Schiff. Computerworld. September 28, 2006.

The San Diego Supercomputer Center is making available more than 400 TB of disk space and even more archival tape space for academic and scientific data. The center has a large production-level infrastructure and 24/7 staff that monitors the system. They can scale to be host large collections over a long period of time in a reliable environment. The center can also easily handle data migration. The resources that a person would need to acquire, such as equipment, staff, and a location, can be handled by the center. The current cost estimate is about $1,500 per terabyte per year . The cost for archival tape is much less, about $500 per terabyte per year, with retrieval time in minutes. "Our focus is on large-scale collections and nonprofit university scientific researchers as well as the digital preservation community."

Digital archiving gains new tool. BBC News. 26 September 2006.

The National Library of New Zealand and the British Library have created a tool that makes it easier to gather and store digital web sites. The web curator tool automates the process of collecting and storing information. It will be available to other organizations as open source by the end of the year. Web harvesting will become more important as more people try to preserve web pages, which is often difficult to do. One obstacle to digital archives is current copyright legislation.

Fujitsu announces petabyte-size disk array with encryption. Sharon Fisher. Computerworld. September 25, 2006.

Fujitsu Computer Systems Corp. has announced a petabyte-size storage array with native encryption. They use 128-bit AES keys, which are also encrypted and stored on the disk drive. The arrays are available now starting at $24,500. Some users with high security needs are uneasy about the possibility of losing access to their data once it is encrypted.

British Library shouts out against unfair DRM. Alun Williams. 26 September 2006.

The British Library is continuing its campaign against the threat of digital rights management technology to the management of UK cultural data. The technology is unforgiving for libraries and public bodies, and threatens innovation, research and our digital heritage. The law does not permit copying of sound or film items for preservation. Without the right for libraries and archives to make copies, she maintained, the UK risks losing a large part of its recorded culture. The recommendations include: existing limitations and exceptions to copyright law should be extended to the digital environment; licenses to digital material should not undermine fair use and preservation purposes. Also, the copyright term for sound recordings should not be extended 'without empirical evidence of the benefits and due consideration of the needs of society as a whole', and that the copyright term for reproducing unpublished works should be the same as for published works. Contracts for digital material generally are more restrictive than existing copyright law and can prevent copying, archiving and access by the visually impaired.

British Library calls for digital copyright action. Tom Espiner. CNET News. September 25, 2006.

The British Library has called for a "serious updating of copyright law to recognize the changing technological environment”. Digital rights management technologies and licensing agreements can impose restrictions that go beyond copyright law. The technology is overriding exceptions to copyright law and can't be circumvented for disabled access or preservation; the technology doesn't expire as does traditional copyright. These restrictions can be particularly damaging for academic research.

Weekly readings - 29 September 2006

Imaging technology restores 700-year-old sacred Hindu text. Physics.org. September 19, 2006.

Imaging techniques are being used to preserve an ancient Hindu text that is deteriorating due to age and improper storage and handling. The images are then being processed and stitched together. This will make opening the fragile book unnecessary in the future. The images are being stored electronically, in printed form, and etched on silicon wafers.

Brother, Can You Spare a Terabyte? Jennifer Schiff. Computerworld. September 28, 2006.

The San Diego Supercomputer Center is making available more than 400 TB of disk space and even more archival tape space for academic and scientific data. The center has a large production-level infrastructure and 24/7 staff that monitors the system. They can scale to be host large collections over a long period of time in a reliable environment. The center can also easily handle data migration. The resources that a person would need to acquire, such as equipment, staff, and a location, can be handled by the center. The current cost estimate is about $1,500 per terabyte per year . The cost for archival tape is much less, about $500 per terabyte per year, with retrieval time in minutes. "Our focus is on large-scale collections and nonprofit university scientific researchers as well as the digital preservation community."

Digital archiving gains new tool. BBC News. 26 September 2006.

The National Library of New Zealand and the British Library have created a tool that makes it easier to gather and store digital web sites. The web curator tool automates the process of collecting and storing information. It will be available to other organizations as open source by the end of the year. Web harvesting will become more important as more people try to preserve web pages, which is often difficult to do. One obstacle to digital archives is current copyright legislation.

Fujitsu announces petabyte-size disk array with encryption. Sharon Fisher. Computerworld. September 25, 2006.

Fujitsu Computer Systems Corp. has announced a petabyte-size storage array with native encryption. They use 128-bit AES keys, which are also encrypted and stored on the disk drive. The arrays are available now starting at $24,500. Some users with high security needs are uneasy about the possibility of losing access to their data once it is encrypted.

British Library shouts out against unfair DRM. Alun Williams. 26 September 2006.

The British Library is continuing its campaign against the threat of digital rights management technology to the management of UK cultural data. The technology is unforgiving for libraries and public bodies, and threatens innovation, research and our digital heritage. The law does not permit copying of sound or film items for preservation. Without the right for libraries and archives to make copies, she maintained, the UK risks losing a large part of its recorded culture. The recommendations include: existing limitations and exceptions to copyright law should be extended to the digital environment; licenses to digital material should not undermine fair use and preservation purposes. Also, the copyright term for sound recordings should not be extended 'without empirical evidence of the benefits and due consideration of the needs of society as a whole', and that the copyright term for reproducing unpublished works should be the same as for published works. Contracts for digital material generally are more restrictive than existing copyright law and can prevent copying, archiving and access by the visually impaired.

British Library calls for digital copyright action. Tom Espiner. CNET News. September 25, 2006.

The British Library has called for a "serious updating of copyright law to recognize the changing technological environment”. Digital rights management technologies and licensing agreements can impose restrictions that go beyond copyright law. The technology is overriding exceptions to copyright law and can't be circumvented for disabled access or preservation; the technology doesn't expire as does traditional copyright. These restrictions can be particularly damaging for academic research.

Weekly readings - 22 September 2006

Preserving Information, Not Formats. Bonita Wilson. D-Lib Magazine. September 2006.

In one library there is a concern about staff and patrons about what to do with materials for which there is no more space. Just because an item has not circulated for a time does not mean it is not valuable. If the item is digitized can that be as reliably retained as the print copy? Deciding what to digitize and what to discard must be looked at carefully. “In many ways, dealing with materials that have existed solely in digital format is easier than contemplating what to do with print materials for which there is no longer space or budget available for maintenance. In the end, however, the critical consideration is how to preserve the information, not the format in which it exists.”

Repository Librarian and the Next Crusade: The Search for a Common Standard for Digital Repository Metadata. Beth Goldsmith, Frances Knudson. D-Lib Magazine. September 2006.

There are a lot of metadata standards within the digital and repository communities. The metadata from different sources can be difficult to use and combine. This example is of a team trying to decide what metadata standard to use. They decided it should be XML-based. Three requirements for a uniform standard for digital repository metadata include:

1. Granularity: the ability to differentiate data elements and maintain context between them

2. Transparency: interoperability

3. Extensibility: ability to grow and meet unseen needs

Other desired features were: support for hierarchical data structures, cooperative management of the standard, support for simple and complex use, and simplicity training or existing experience with the standard. MARCXML was selected as a uniform metadata standard for the digital repository because of its relative maturity in the XML standards world, its familiarity in the library community, and its ability to blend well with modern mark-up technologies.

USB flash drives are failing. Bruce Hoard. Computerworld. September 15, 2006.

Failures of USB flash memory drives are increasing because of quality-control problems. The drives may have additional fragmentation problems. These drives are expected to last for an average of 100,000 read-write cycles. However the fragmentation problems may become more of a threat with the increased size of the flash memory.

Cornell University and Publishers announce new copyright guidelines governing use of digital course materials. Press release. September 19, 2006.

The Association of American Publishers and Cornell announced a new set of copyright guidelines to govern the use of electronic course materials on the campus system. The joint guidelines make it clear that faculty must obtain permission to distribute electronic works in the same way as they do with hard-copy formats. Instructors should use technical means to limit access to copyrighted electronic course content. These works should include appropriate copyright statements.

Inventors try single disc for both new DVD formats. Jeffrey Goldfarb. Computerworld. September 20, 2006.

Three Warner Bros. employees have filed a patent application for a disc that would play the Blu-ray and HD DVD formats. Information on the DVD would be stored at different depths, depending on the technology. Blu-ray discs store information only 0.1mm from the surface while HD-DVDs store it at 0.6mm. By using reflective films, the lasers could read the top layer and "see through" to the lower one if needed. Additional information could also be stored on the other side of the disc.

Weekly readings - 22 September 2006

Preserving Information, Not Formats. Bonita Wilson. D-Lib Magazine. September 2006.

In one library there is a concern about staff and patrons about what to do with materials for which there is no more space. Just because an item has not circulated for a time does not mean it is not valuable. If the item is digitized can that be as reliably retained as the print copy? Deciding what to digitize and what to discard must be looked at carefully. “In many ways, dealing with materials that have existed solely in digital format is easier than contemplating what to do with print materials for which there is no longer space or budget available for maintenance. In the end, however, the critical consideration is how to preserve the information, not the format in which it exists.”

Repository Librarian and the Next Crusade: The Search for a Common Standard for Digital Repository Metadata. Beth Goldsmith, Frances Knudson. D-Lib Magazine. September 2006.

There are a lot of metadata standards within the digital and repository communities. The metadata from different sources can be difficult to use and combine. This example is of a team trying to decide what metadata standard to use. They decided it should be XML-based. Three requirements for a uniform standard for digital repository metadata include:

1. Granularity: the ability to differentiate data elements and maintain context between them

2. Transparency: interoperability

3. Extensibility: ability to grow and meet unseen needs

Other desired features were: support for hierarchical data structures, cooperative management of the standard, support for simple and complex use, and simplicity training or existing experience with the standard. MARCXML was selected as a uniform metadata standard for the digital repository because of its relative maturity in the XML standards world, its familiarity in the library community, and its ability to blend well with modern mark-up technologies.

USB flash drives are failing. Bruce Hoard. Computerworld. September 15, 2006.

Failures of USB flash memory drives are increasing because of quality-control problems. The drives may have additional fragmentation problems. These drives are expected to last for an average of 100,000 read-write cycles. However the fragmentation problems may become more of a threat with the increased size of the flash memory.

Cornell University and Publishers announce new copyright guidelines governing use of digital course materials. Press release. September 19, 2006.

The Association of American Publishers and Cornell announced a new set of copyright guidelines to govern the use of electronic course materials on the campus system. The joint guidelines make it clear that faculty must obtain permission to distribute electronic works in the same way as they do with hard-copy formats. Instructors should use technical means to limit access to copyrighted electronic course content. These works should include appropriate copyright statements.

Inventors try single disc for both new DVD formats. Jeffrey Goldfarb. Computerworld. September 20, 2006.

Three Warner Bros. employees have filed a patent application for a disc that would play the Blu-ray and HD DVD formats. Information on the DVD would be stored at different depths, depending on the technology. Blu-ray discs store information only 0.1mm from the surface while HD-DVDs store it at 0.6mm. By using reflective films, the lasers could read the top layer and "see through" to the lower one if needed. Additional information could also be stored on the other side of the disc.