This is to make some comments and proposals for the DLM-meeting in Washington. I think that the general aspects have been addressed perfectly by the paper from John Ewing. My aim is to highlight some action items of general importance. Possibly groups to work on that could be installed, hoping to reach more progress in the co-ordination of the project and to pass from theoretical considerations to first practical steps.
The idea what should be covered by the DLM is quite vague. There are ongoing projects which partially will take part in the meeting and which have selected items for retrodigitization according to different aspects. These patches of the global DLM will be defined, but they cannot serve as a model for a comprehensive coverage of mathematical publications. Hence the first question to be addressed is:
Do we really want to cover all mathematical publications world-wide by the DLM?
If not so, we have to discuss the selection criteria. But even we have to decide on selection criteria when finally the DLM should cover all mathematics, because not everything could be done immediately and a time schedule for building up the DLM step by step requires an order and hence a selection. This implies that we have to develop a list of document types to be covered by DLM, where the following list is oriented at printed publications:
What are the documents to be covered by the DLM?
Probably the items 1 and 5 are the easiest to be handled systematically.
How can we determine all documents belonging to one of these items?
Probably all these methods will have to be applied to be really comprehensive
Which publications may be considered as a part of mathematics according to subject area?
Who should take part in arranging a list of contents and who should administrate such a list?
Should we nor care about such a list at all and digitise what will be just in our mind or easily available?
Presumably the DLM will be based on distributed repositories. These will have their own access facilities. In addition various options for integrated access to the distributed sites could be imagined.
For example, one simple access may be provided by links from the current reviewing databases in mathematics. They also may serve as the background for a navigation tool for the DLM. These aspects will be addressed in a separate description.
But in addition to this at least one comprehensive integrated access structure should be developed for the DLM, not only because this is an essential requirement for a digital library, but also because more aspects could be addressed by such an access facility than it is done by a reviewing database. Such a structure obviously requires a co-ordination of the metadata produced at the different sites caring about a repository for the DLM. For pursuing a common approach the following problems have to be addressed:
What are the metadata structures used by the current retrodigitization projects? Is there a core group where these structures are more or less compatible already? Are there current providers of a repository of interest to the DLM which do not want to be integrated into the access structure? Do they reveal their metadata structure, and if so, is this compatible with that of the others?
After that the possibility of a joint metadata format could be investigated. The current metadata may be converted into this.
The access structure should take into account the (probably different) business models of the repositories in the background. Free access will be highly desirable, but costs for maintenance and further development of the different repositories. cannot be neglected.