diff --git a/activesupport/lib/active_support/ordered_hash.rb b/activesupport/lib/active_support/ordered_hash.rb
index 8edd3960c7b40d072029097c91576cea75afcbd3..1a3693f766de84dc46ce418c73b3eaef54f797c2 100644
--- a/activesupport/lib/active_support/ordered_hash.rb
+++ b/activesupport/lib/active_support/ordered_hash.rb
@@ -5,16 +5,20 @@
end
module ActiveSupport
- # The order of iteration over hashes in Ruby 1.8 is undefined. For example, you do not know the
- # order in which +keys+ will return keys, or +each+ yield pairs. ActiveSupport::OrderedHash
- # implements a hash that preserves insertion order, as in Ruby 1.9:
+ # ActiveSupport::OrderedHash implements a hash that preserves
+ # insertion order.
#
# oh = ActiveSupport::OrderedHash.new
# oh[:a] = 1
# oh[:b] = 2
# oh.keys # => [:a, :b], this order is guaranteed
#
- # ActiveSupport::OrderedHash is namespaced to prevent conflicts with other implementations.
+ # Also, maps the +omap+ feature for YAML files
+ # (See http://yaml.org/type/omap.html) to support ordered items
+ # when loading from yaml.
+ #
+ # ActiveSupport::OrderedHash is namespaced to prevent conflicts
+ # with other implementations.
class OrderedHash < ::Hash
def to_yaml_type
"!tag:yaml.org,2002:omap"