Re: Fw: New Catalog XML Draft

----- Original Message -----
Cc: <thredds@xxxxxxxxxxxxxxxx>
Sent: Monday, May 20, 2002 8:51 PM

> # > Internal DTD rules override external DTD rules, but you can have both
> # > the same document. Internal DTD declarations come after the external
> # > call and between square brackets.
> The following clarification may not be relevant for your work, but
> just in case: The internal DTD is physically after the external DTD
> reference in the XML document, but the internal DTD is processed
> first. Strictly speaking, it does not override (i.e., redefine)
> external definitions but rather declares them first and thereby
> forbids the external DTD from declaring them. Therefore, you cannot
> use the internal DTD as a way to modify elements defined in the
> external DTD--you can only extend it by defining new elements.

I am still unclear: if the internal DTD declares an element, what happens if
the external DTD does also? If the second declaration gets ignored, isnt
that like overriding?

> The most error-prone part of the OGC Web Map Service metadata XML is
> the provision for vendor-specific elements via a required but usually
> empty %ENTITY declaration in the internal DTD. I have not yet
> determined whether XML Schema will let us do this more effectively.
> -Jeff DLB

Are you referring to this line in the Capabilities DTD? It seems very
similar to what Joe was trying to do. Were you trying to make a standard
list that could be extended? What was error-prone about it?

BTW, where is the "sample XML" mentioned below?

<!-- This WMT-wide list of possible output formats can be redefined by
individual servers; see the sample XML. -->

<!ENTITY % KnownFormats " GIF | JPEG | PNG | WebCGM | SVG | GML.1 | GML.2 |

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