This proposal is an update to 4421066.  It modifies an interface
 change that has not yet been publically released.


 Background

 The javadoc tool maintains backward compatibility for "legacy" doclets --
 those not aware of the Tiger language features.  It modifies the
 results of a number of methods to match as closely as possible the
 pre-Tiger results.  For example, type parameters are elided.

 The javadoc tool must be able to determine if a doclet supports the
 1.5 language features.  It currently relies on a marker interface
 Doclet15 for new doclets to implement.  The name Doclet15, and
 its use as a marker interface, are ugly and nonintuitive.  It would be
 ideal if we could have a Doclet interface for doclets to implement.
 Unfortunately the class name Doclet is already taken by a so-called
 "example" doclet, and the entry point methods of a doclet are all (for
 no good reason) static.


 Proposal

 Drop Doclet15.  Instead, a doclet should indicate its language version
 by supplying a languageVersion method.  This has the side benefit of
 being extensible for possible language changes in, say, Mustang.  The
 "example" Doclet class has the following addition:

     /**
      * Return the version of the Java Programming Language supported
      * by this doclet.
      * <p>
      * This method is required by any doclet supporting a language version
      * other than 1.1.
      *
      * @return	the language version supported by this doclet;
      *		default is 1.1
      * @since 1.5
      */
     public static LanguageVersion languageVersion() {
	 return LanguageVersion.JDK1_1;
     }

 LanguageVersion is defined as:

     /**
      * Java Programming Language version.  The constants of this enum
      * identify the JDK and J2SE releases containing language changes
      * relevant to doclets.
      * <p>
      * All doclets support at least the 1.1 language version.
      * The first release subsequent to this with language changes
      * affecting doclets is 1.5.
      *
      * @since 1.5
      */
     public enum LanguageVersion {

	 /** JDK 1.1:  added nested classes and interfaces. */
	 JDK1_1,

	 /** J2SE 1.5:  added generic types, enums, varargs, and annotations. */
	 J2SE1_5
     }