(Almost) All you wanted to know about METS(and were afraid to ask?)The OAIS preservation data modelThe DSpace Data Model (see the mapping to METS in the SIP profile)Determining the model implied by your use caseStructure of a METS documentThe METS SchemaThe current METS schema (1.5) is to be found here: http://www.loc.gov/standards/mets/mets.xsdThe general METS Profile SchemaThe specific METS Application Profile SchemaYour specific METS Application Profile SchemaYour METS template and the sample document(Almost) All you wanted to know about METS(and were afraid to ask?)The following document is meant to clarify the METS and XML features you will use to encode your profile and to create an example document to serve as a template for use with XMetaL or other editor. There are useful tutorials available, and you are encouraged to use them, but not all will be directly relevant to your individual object type. If you have not already seen it, review this overview Library of Congress METS tutorial document:http://www.loc.gov/standards/mets/METSOverview.htmlAnother useful document is the METS Profile Components document at:http://www.loc.gov/standards/mets/profile_docs/components.htmlYou should find very helpful the more detailed document from which this is drawn, the earliest version (1.1) of the METS profile, which includes as its Appendix 1 the XML Schema that defines METS profile documents and as its Appendix 2 a fully-worked out METS profile with itsown Document/template example:http://www.loc.gov/standards/mets/profile_docs/METS.profile.requirements.1-1.rtfThe Case Studies linked to from http://www.odl.ox.ac.uk/projects/projects_mets.htm provide us with a model of the process you will need to follow to decide what your data model is and how to map it in a METS document. These case studies pose five standard questions for each object type:Questions to ask when implementing this collection in METS;1. What facilities do you want to offer your users when using this collection?2. What extension schemas should you use for descriptive and administrative metadata?3. What standards would you adopt for metadata content (name authorities, subject headings)?4. What files will you include in your <fileSec> and how will they be arranged?5. How will you arrange your <structMap>?Our concern is to be able to map your object type as represented by your use case into the OAIS preservation data model, the DSpace data model, and the METS framework.The OAIS preservation data modelThere are basically four kinds of elements in the OAIS model:1) Reference Information: enumerates and describes identifiers assigned to the content information such that it can be referred to unambiguously, both internally and externally to the archive (e.g., ISBN, URN). In other words, this is the unique identifier for the object. You must have one, or you’ll never find the object again; although the system’s unique identifier may be assigned by the system on ingest, the system itself must receive all objects as uniquely identified to begin with.2) Provenance Information: documents the history of the content information (e.g., its origins, chain of custody, preservation actions and effects) and helps to support claims of authenticity andintegrity. 3) Context Information: documents the relationship of the content information to its environment (e.g., why it was created, relationships to other content information). The second 1item is especially important: it refers to the relationships between component files of a complex object.4) Fixity Information: documents authentication mechanisms used to ensure that the content information has not been altered in an undocumented manner (e.g., checksum, message digest, digital signature).DSpace Data Model DiagramThe DSpace Data Model (see the mapping to METS in the SIP profile)See the diagram above for the whole DSpace data model, found here: http://www.dspace.org/technology/system-docs/functional.html; we need to be concerned with 2the following parts of it in order to understand better the DSpace METS profile that will serve you as a basis:1) Collection: In DSpace, collections are groupings of related content (not a novel idea to us).2) Item: Each collection in DSpace is composed of items, which are the basic archival elements of the archive. Each item is owned by one collection. According to the profile, an item is coveredby one METS document. The MODS metadata for the item level itself is pointed to in the first <div> under the <structMap>. Items are further subdivided into named bundles of bitstreams. 3) Bundle: The bundle structure is reflected in the METS <structMap> and in the <fileSec>, where the files are supposed to be organized into <fileGrp>s by bundle type. The DSpace METS profile specifies the following named bundles:- CONTENT -- the bundle with the original, deposited bitstreams; note that it is possible that there may be only one bitstream in the content bundle.Some of the following bundles are actually created by the DSpace system and are added to the content bundle under the item, but when a METS SIP document is used, it is possible to define them explicitly:- THUMBNAIL -- thumbnails of any image bitstreams; many items will have no need of these.- TEXT (EXTRACTED) -- extracted full-text from bitstreams in ORIGINAL, for indexing; many items will have no need for these.- LICENSE -- contains the deposit license that the submitter granted to the host organization; in other words, specifies the rights that the hosting organization has to manage the object(s).- CC_LICENSE -- contains the distribution license, if any (a Creative Commons license) associated with the item. This license specifies what end users downloading the content can do with the content.- METADATA – can be used to hold serialized metadata that is not otherwise placed in the DSpace metadata database tables.4) Bitstream: Bitstreams are, as the name suggests, streams of bits, usually ordinary computer files, and expressed as METS <file>s. Each bitstream is also associated with one Bitstream Format. Because preservation services may be an important aspect of the DSpace service, it is important to capture the specific formats of files that users submit, so they are provided as part ofthe METS metadata. In DSpace, a bitstream format is a unique and consistent way to refer to a particular file format. An integral part of a bitstream format is an either implicit or explicit notionof how material in that