I’ve heard about XML Catalogs before, but never in a context that piqued my interest enough such that I’d want to go learn what they were. Thanks to Norm Walsh’s description of them today in his weblog, I now know.
The idea, it seems, is that you need different identifiers in different contexts. So, for example, a http URL for some document won’t be usable when you’re offline, so you need a way to package that identifier, with the local one on the file system.
My view is that while I agree this is a problem, I don’t think new standards are required to fix it. I suggest that better technology is what is required.
“http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd” is an identifier for a DocBook DTD, and independent of the online status of your notebook, it remains an identifier for that DocBook DTD. What’s needed are operating systems, browsers, and network libraries that, when offline and asked for a representation of the resource identified by that URI, returns a cached representation.
Another consequence of this is that “File->Save As” in a browser should be de-emphasized. I’d prefer it be just “Save” or “Store” or something like that where the user isn’t prompted for a file name. The implication being that the file already has an identifier, so why does it need a different name on my computer? Obviously you’d still want access to “File->Save As” in some cases, but I don’t believe it’s what most people need most of the time.