= YANG Tools support for YANG 1.1
Tony Tkacik <ttkacik@cisco.com>
:toc:
:rfc6020: https://tools.ietf.org/html/rfc6020
:rfc6020bis: https://tools.ietf.org/html/draft-ietf-netmod-rfc6020bis

== Introduction

=== Significant changes

.Summary of Changes from draft
-  Changed the YANG version from "1" to "1.1".
-  Made the `yang-version` statement mandatory.
-  Made noncharacters illegal in the built-in type `string`.
-  Defined the legal characters in YANG modules.
-  Changed the rules for the interpretation of escaped characters in
  double quoted strings.  This is an backwards incompatible change
  from YANG version 1.  A module that uses a character sequence that
  is now illegal must change the string to match the new rules.
-  An unquoted string cannot contain any single or double quote
  characters.  This is an backwards incompatible change from YANG
  version 1.
-  Extended the `if-feature` syntax to be a boolean expression over
  feature names.
-  Allow `if-feature` in `bit`, `enum`, and `identity`.
-  Allow `if-feature` in `refine`.
-  Made `when` and `if-feature` illegal on list keys.
-  Allow `choice` as a shorthand case statement.
-  Added a new substatement `modifier` to pattern.
-  Allow `must` in `input`, `output`, and `notification`.
-  Allow `require-instance` in leafref.
-  Allow `augment` to add conditionally mandatory nodes.
-  Added a set of new XPath functions.
-  Clarified the XPath context's tree.
-  Defined the string value of an identityref in XPath expressions.
-  Clarified what unprefixed names mean in leafrefs in typedefs.
-  Allow identities to be derived from multiple base identities.
-  Allow enumerations and bits to be subtyped.
-  Allow leaf-lists to have default values.
-  Allow non-unique values in non-configuration leaf-lists.
-  Use [RFC7405] syntax for case-sensitive strings in the grammar.
-  Changed the module advertisement mechanism.
-  Changed the scoping rules for definitions in submodules.  A
   submodule can now reference all definitions in all submodules that
   belong to the same module, without using the `include` statement.
-  Added a new statement `action` that is used to define operations
   tied to data nodes.
-  Allow notifications to be tied to data nodes.
-  Added a new data definition statement `anydata`.
-  Allow types `empty` and `leafref` in unions.
-  Allow type `empty` in a `key`.