----- Original Message ----- From: "Jeff de La Beaujardiere" <address@hidden> To: "John Caron" <address@hidden> Cc: <address@hidden> Sent: Monday, May 20, 2002 8:51 PM Subject: Re: Fw: New Catalog XML Draft > > # > Internal DTD rules override external DTD rules, but you can have both in > # > the same document. Internal DTD declarations come after the external DTD > # > 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 | GML.3 | WBMP | WMS_XML | MIME | INIMAGE | TIFF | GeoTIFF | PPM | BLANK " >
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