The namespace provides support for prepopulating the cache with DTDs or XML streams.
XmlPreloadedResolver is used as a resolver when automatic calls to the network are not desired or are not possible. For example, this type can be used for loading cached external DTDs. Another scenario is loading XHTML and using XmlPreloadedResolver to preload well-known DTDs that are defined in XHTML 1.0. Preloading a well-known DTD does not invoke any network connections because these DTDs are already embedded in the System.Xml.Utils assembly. Currently, XmlPreloadedResolver includes XHTML 1.0 and RSS 0.91 DTDs.
XmlKnownDtd.Xhtml10 specifies that the T:System.Xml.Resolvers.XmlPreloadedResolver will recognize DTDs and entities that are defined in XHTML 1.0. For more information about XHTML, see the XHTML 1.0 specification.
XmlKnownDtd.Rss091 specifies that the T:System.Xml.Resolvers.XmlPreloadedResolver will recognize DTDs and entities that are defined in RSS 0.91.
XmlKnownDtd.All specifies that the XmlPreloadedResolver will recognize all currently supported DTDs. This is the default behavior.
XmlKnownDtd.None specifies that the XmlPreloadedResolver will not recognize any of the predefined DTDs.
When the XmlPreloadedResolver preloads a well-known DTD, it does not invoke network connections because the DTDs are already embedded in the System.Xml.Utils assembly.