[DAS2] DAS/2 questions

[Cyrus Harmon]

Hello DAS folks,

I've been looking at the DAS/2 spec and have a few questions/comments:

[0. I'm assuming that DAS2 is the thing to use and that the version of  
the spec found here:http://biodas.org/documents/das2/das2_get.htmlis  
as close to normative/current/etc... as can be found.]

1. The table at the beginning of http://biodas.org/documents/das2/das2_get.html 
  lists 4 types: sources, segments, types and features. Section 1.2  
says "Each of the five new formats has its own MIME type." and then  
goes on to list three: "application/x-das-sources+xml, application/x- 
das-features+xml, application/x-das-types+xml". Are there three, four  
or five types?

2. It seems to me that it would be worth splitting up the transport  
issues from the filespec. Why not have a spec for the XML and a spec  
for DAS-over-http(s)? This seems trivial (although it of course  
requires a bit more work to maintain two resources rather than one),  
but I could be wrong. Clearly, some of the sensible values that a DAS  
server would return are based on things that are established at the  
time of the request, but the spec should still allow for construction  
of DAS/2 files without regard to the particular transport layer.  
Perhaps there's a need for establishing some set of criteria like well- 
formed-ness and validity that describe increasing levels of  
"correctness" and one could enforce the transport related issues at  
one of the higher levels.

3. DTDs? Searching for the string DTD in the document turns up empty.  
Is this by design?

4. Without a DTD it's a bit hard to read (well, the DTD might not help  
too much, but it does give some constraints) the specs for things like  
SOURCES. I'd suggest that the detailed document sections lead off with  
some sort of formal-ish representation of what is in that document (or  
document element) and then follow up with the examples. It seems that  
there is a fairly small number of document elements for each document  
type. Can we list those in their own sections in section 3.X as 3.X.Y  
and in these sections be explicit about what is in each document  
element here?

Thanks,

Cyrus