Greetings, On behalf of the Digital Library Working Group, University Libraries, University of Minnesota, I am forwarding some comments about the proposed METS Standard. These comments were written by Charles F. Thomas, Digital Projects Coordinator at the University of Minnesota, and then reviewed by the Digital Library Working Group. I will send our comments embedded as text below, and attach a MS Word file with the same information. Thank you for the opportunity to comment on the METS standard. Josephine Crawford, chair Digital Library Working Group University Libraries University of Minnesota * * * * * * * * * * A Response to the METS Proposed Standard From the University of Minnesota Libraries Digital Library Working Group 05/21/02 The Metadata Encoding Transmission Standard (METS) offers an extensible and scalable model for organizing metadata about digital objects. Its ancestral roots in the Making of America project are apparent; METS offers a rational solution for managing large bodies of individual electronic files that are closely interrelated. In particular, we see METS as a vital precursor to next-generation presentation and navigation tools for digital objects such as digitized books and other information-bearing-objects that consist of many discrete parts. METS is flexible in that it permits any xml-based metadata schema to be employed within its "wrapper" structure. The creators of METS also have incorporated features that may be of benefit in other functions such as digital archiving. We do offer two constructive criticisms for the Digital Library Federation. The first is that METS is based entirely upon an XML Schema Description (XSD). This choice is understandable, XML Schema are themselves XML-based and hold the promise of easier data and data structure interchange. However, we would suggest that a Document Type Definition (DTD) version of the METS standard co-exist with the XSD statement of its structure. XML Schema undoubtedly offer much, but a large body of middle-of-the-road pragmatists will hesitate to adopt XML Schema at this time, because of its recent vintage and perceived instability. DTDs, conversely, are much more established as a way to define structure for encoding. If the XSD version of METS took advantage of some of the advantages XML Schema offer, such as data-typing, then this would not be possible. However, since METS is designed to be a simple, flexible wrapper for metadata (and potentially even digital object content), a co-existing DTD-based statement of the METS structure and rules should promote faster adoption among the XML communities who still prefer DTDs. Our second comment is closely related to the first. The METS overview and tutorials frequently mention the capability of METS to actually wrap Base-64 binary content into the metadata descriptions, for such purposes as digital archiving. Strategies for permanently associating metadata with digital objects have continued at least since the earliest discussion that led to the Dublin Core metadata standard. To date, we have witnessed multiple approaches to hard and soft associations between digital objects and their metadata. One common way of doing this is through defining both metadata and digital objects as related "entities." Defining entities is a useful way of modularizing object and metadata management. Unfortunately, XML Schema do not support the definition of entities such as text files, binary objects, etc. This is one main reason that the XML Schema has never purported to replace DTDs, which do permit the definition of entities. The University of Minnesota Libraries Digital Library Working Group appreciates the opportunity to comment on the proposed METS standard. It demonstrates leadership by proposing a flexible and extensible means of storing, referencing and interchanging metadata. We feel that stewardship and maintenance of METS by the Library of Congress also is a very positive sign. Our few concerns and suggestions deal mainly with accommodation of a large body of existing institutions and practices, and the ability to manage metadata and objects effectively. We support METS as a standardized means of exchanging information, and hope that our suggestions will prove useful.