[tdwg-content] minor issues with DWCA Validator

[Matt Yoder]

Hi there,

As we implement a DWCA generator I've stumbled on a number of minor
bits in reference to http://tools.gbif.org/dwca-validator/.  I
understand how to get around these things, but resolving them might
lower the barrier to entry for others.

When I validate a DWCA

1)   then I see a link 'Dublin Core'
(http://code.google.com/p/darwincore/source/browse/trunk/dwca-reader/src/test/resources/metadata/worms_dc.xml)
        that link is broken

2)   and I have no metadata file
         then the instructions under Metadata as to what to do to
resolve the problem (i.e. do next) are essentially unusable for the
non-technically oriented

3)   and I read this: "All null values are empty strings." in green
   and I get this immediately after "Error scanning records:
java.lang.NullPointerException"
       then I am confused
            I would be less confused with a literal example of the issue

4) and I have an id column in [0],
         and that id column is mapped to nothing
         then I see under Darwin Core Occurrence 'Core Record ID
mapped to nothing'
            and I think 'OK'
          then at the bottom of that list I see 'Unknown term
http://purl.org/dc/terms/identifier mapped to column 0'
             and I am confused as to this (auto-mapping?) that has a
namespace (http://purl.org/dc/terms/), and a term (identifier), both
of which I have not referenced
               and I don't know what todo


Cheers,
Matt