A method to request the first DOM implementation that supports the specified features.

  A method to request the first DOM implementation that supports the
specified features.
Returns: The first DOM implementation that support the desired features, or null if this source has none.
Parameters:
- features - A string that specifies which features and versions are required. This is a space separated list in which each feature is specified by its name optionally followed by a space and a version number. This method returns the first item of the list returned by getDOMImplementationList. As an example, the string "XML 3.0 Traversal +Events 2.0" will request a DOM implementation that supports the module "XML" for its 3.0 version, a module that support of the "Traversal" module for any version, and the module "Events" for its 2.0 version. The module "Events" must be accessible using the method Node.getFeature() and DOMImplementation.getFeature().

  A method to request a list of DOM implementations that support the specified features and versions, as specified in .

  A method to request a list of DOM implementations that support the
specified features and versions, as specified in .
Returns: A list of DOM implementations that support the desired features.
Parameters:
- features - A string that specifies which features and versions are required. This is a space separated list in which each feature is specified by its name optionally followed by a space and a version number. This is something like: "XML 3.0 Traversal +Events 2.0"