Define protected to apply to fields

pkg/meta/lib/meta.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Constants for use in metadata annotations such as `@protected`.
 ///
 /// See also `@deprecated` and `@override` in the `dart:core` library.
 ///
 /// Annotations provide semantic information that tools can use to provide a
 /// better user experience. For example, an IDE might not autocomplete the name
 /// of a function that's been marked `@deprecated`, or it might display the
 /// function's name differently.
 ///
 /// For information on installing and importing this library, see the
 /// [meta package on pub.dartlang.org] (http://pub.dartlang.org/packages/meta).
 /// For examples of using annotations, see
 /// [Metadata](https://www.dartlang.org/docs/dart-up-and-running/ch02.html#metadata)
 /// in the language tour.
 library meta;
 
-/// Used to annotate an instance method `m` in a class `C`. Indicates that `m`
+/// Used to annotate an instance member (method, getter, setter, operator, or
+/// field) `m` in a class `C`. If the annotation is on a field it applies to the
+/// getter and setter, if appropriate, implied by the field. Indicates that `m`
 /// should only be invoked from instance methods of `C` or classes that extend
 /// or mix in `C`, either directly or indirectly. Additionally indicates that
 /// `m` should only be invoked on `this`, whether explicitly or implicitly.
 ///
 /// Tools, such as the analyzer, can provide feedback if an invocation of a
-/// method marked as being protected is used outside of an instance method
+/// member marked as being protected is used outside of an instance member
 /// defined on a class that extends or mixes in the class in which the protected
-/// method is defined, or that uses a receiver other than `this`.
+/// member is defined, or that uses a receiver other than `this`.
+///
+/// Tools can also provide feedback if the annotation is used on anything other
+/// than an instance member.
 const _Protected protected = const _Protected();
 
 class _Protected {
   const _Protected();
 }