/**
 * Revisions log for unique_field
 */

version 2009/03/06 (5.x-1.0)
-- fixed query generation for grouping OR clauses
-- altered appearance of unique fields settings on the content type form:
  moved unique field section to the bottom, added descriptions
-- fixed compatibility with cck_field_perms [thanks to skassam]

version 2009/02/09 (5.x-1.0-beta1)
-- fixed handling of multiple values per CCK field
-- added option for showing the nodes that match when a duplicate
  value is found [thanks to crea]
-- fixed handling of node revisions
-- rewrote query generation routine
-- added node author as a query field
-- added hook_uninstall support for removing the module's variables
  [thanks to markus_petrux]
-- improved compliance with coding standards [thanks to deekayen]

version 2008/10/24
-- added check for content.module for CCK-dependent code [thanks to sigsby]
-- removed all MySQL database-specific code [thanks to rssaddict]

version 2008/03/15
-- fixed to use node title label from node type data [thanks to tj2653]

version 2008/03/14
-- changed behavior so that if a field value is null or empty it matches
  no other node (including other nodes with null or empty values)
  [thanks to scedwar]

version 2008/03/13
-- fixed support for node and user reference fields in single node scope,
  verified support for both in other scopes

version 2008/03/12
-- added single node scope to require that specified fields on a node
  have unique values
-- improved error messages to specify which fields must be unique
  and which include duplicates

version 2008/02/22
-- fixed queries to support table prefixes

version 2008/02/18
-- initial release

TO-DO
-- fix use of t() to eliminate the use of variables inside
-- fix consistent case-sensitivity of database queries, add option
  for whether to use case-sensitive comparisons (see #333137)
-- add validation before submission via AJAX (see #338744)
-- add taxonomy vocabulary/term as query field and scope (see #227254)
-- add views as a query scope (see #223792)
-- allow multiple types of constraints (see #347327)