NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

= KEY ====================
    # Breaks back-compat
    ! Feature
    - Bugfix
      + Sub-comment
    . Internal change
==========================

3.1.0, unknown release date
! Autoload support added
- Autoclose now operates iteratively, i.e. <span><span><div> now has
  both span tags closed.
. Plugins now get their own changelogs according to project conventions.
. Convert tokens to use instanceof, reducing memory footprint and
  improving comparison speed.
. Dry runs now supported in SimpleTest; testing facilities improved

3.0.0, released 2008-01-06
# HTML Purifier is PHP 5 only! The 2.1.x branch will be maintained
  until PHP 4 is completely deprecated, but no new features will be added
  to it.
  + Visibility declarations added
  + Constructor methods renamed to __construct()
  + PHP4 reference cruft removed (in progress)
! CSS properties are now case-insensitive
! DefinitionCacheFactory now can register new implementations
! New HTMLPurifier_Filter_ExtractStyleBlocks for extracting <style> from
  documents and cleaning their contents up. Requires the CSSTidy library
  <http://csstidy.sourceforge.net/>. You can access the blocks with the
  'StyleBlocks' Context variable ($purifier->context->get('StyleBlocks')).
  The output CSS can also be "scoped" for a specific element, use:
  %Filter.ExtractStyleBlocksScope
! Experimental support for some proprietary CSS attributes allowed:
  opacity (and all of the browser-specific equivalents) and scrollbar colors.
  Enable by setting %CSS.Proprietary to true.
- Colors missing # but in hex form will be corrected
- CSS Number algorithm improved
- Unit testing and multi-testing now on steroids: command lines,
  XML output, and other goodies now added.
. Unit tests for Injector improved
. New classes:
  + HTMLPurifier_AttrDef_CSS_AlphaValue
  + HTMLPurifier_AttrDef_CSS_Filter
. Multitest now has a file docblock

2.1.3, released 2007-11-05
! tests/multitest.php allows you to test multiple versions by running
  tests/index.php through multiple interpreters using `phpv` shell
  script (you must provide this script!)
- Fixed poor include ordering for Email URI AttrDefs, causes fatal errors
  on some systems.
- Injector algorithm further refined: off-by-one error regarding skip 
  counts for dormant injectors fixed
- Corrective blockquote definition now enabled for HTML 4.01 Strict
- Fatal error when <img> tag (or any other element with required attributes)
  has 'id' attribute fixed, thanks NykO18 for reporting
- Fix warning emitted when a non-supported URI scheme is passed to the
  MakeAbsolute URIFilter, thanks NykO18 (again)
- Further refine AutoParagraph injector. Behavior inside of elements
  allowing paragraph tags clarified: only inline content delimeted by
  double newlines (not block elements) are paragraphed.
- Buggy treatment of end tags of elements that have required attributes
  fixed (does not manifest on default tag-set)
- Spurious internal content reorganization error suppressed
- HTMLDefinition->addElement now returns a reference to the created
  element object, as implied by the documentation
- Phorum mod's HTML Purifier help message expanded (unreleased elsewhere)
- Fix a theoretical class of infinite loops from DirectLex reported
  by Nate Abele
- Work around unnecessary DOMElement type-cast in PH5P that caused errors
  in PHP 5.1
- Work around PHP 4 SimpleTest lack-of-error complaining for one-time-only
  HTMLDefinition errors, this may indicate problems with error-collecting
  facilities in PHP 5
- Make ErrorCollectorEMock work in both PHP 4 and PHP 5
- Make PH5P work with PHP 5.0 by removing unnecessary array parameter typedef
. %Core.AcceptFullDocuments renamed to %Core.ConvertDocumentToFragment 
  to better communicate its purpose
. Error unit tests can now specify the expectation of no errors. Future
  iterations of the harness will be extremely strict about what errors
  are allowed
. Extend Injector hooks to allow for more powerful injector routines
. HTMLDefinition->addBlankElement created, as according to the HTMLModule
  method
. Doxygen configuration file updated, with minor improvements
. Test runner now checks for similarly named files in conf/ directory too.
. Minor cosmetic change to flush-definition-cache.php: trailing newline is
  outputted
. Maintenance script for generating PH5P patch added, original PH5P source
  file also added under version control
. Full unit test runner script title made more descriptive with PHP version
. Updated INSTALL file to state that 4.3.7 is the earliest version we
  are actively testing

2.1.2, released 2007-09-03
! Implemented Object module for trusted users
! Implemented experimental HTML5 parsing mode using PH5P. To use, add
  this to your code:
        require_once 'HTMLPurifier/Lexer/PH5P.php';
        $config->set('Core', 'LexerImpl', 'PH5P');
  Note that this Lexer introduces some classes not in the HTMLPurifier
  namespace.  Also, this is PHP5 only.
! CSS property border-spacing implemented
- Fix non-visible parsing error in DirectLex with empty tags that have
  slashes inside attribute values.
- Fix typo in CSS definition: border-collapse:seperate; was incorrectly
  accepted as valid CSS. Usually non-visible, because this styling is the
  default for tables in most browsers. Thanks Brett Zamir for pointing
  this out.
- Fix validation errors in configuration form
- Hammer out a bunch of edge-case bugs in the standalone distribution
- Inclusion reflection removed from URISchemeRegistry; you must manually
  include any new schema files you wish to use
- Numerous typo fixes in documentation thanks to Brett Zamir
. Unit test refactoring for one logical test per test function
. Config and context parameters in ComplexHarness deprecated: instead, edit
  the $config and $context member variables
. HTML wrapper in DOMLex now takes DTD identifiers into account; doesn't
  really make a difference, but is good for completeness sake
. merge-library.php script refactored for greater code reusability and
  PHP4 compatibility

2.1.1, released 2007-08-04
- Fix show-stopper bug in %URI.MakeAbsolute functionality
- Fix PHP4 syntax error in standalone version
. Add prefix directory to include path for standalone, this prevents
  other installations from clobbering the standalone's URI schemes
. Single test methods can be invoked by prefixing with __only

2.1.0, released 2007-08-02
# flush-htmldefinition-cache.php superseded in favor of a generic
  flush-definition-cache.php script, you can clear a specific cache
  by passing its name as a parameter to the script
! Phorum mod implemented for HTML Purifier
! With %Core.AggressivelyFixLt, <3 and similar emoticons no longer
  trigger HTML removal in PHP5 (DOMLex). This directive is not necessary
  for PHP4 (DirectLex).
! Standalone file now available, which greatly reduces the amount of
  includes (although there are still a few files that reside in the
  standalone folder)
! Relative URIs can now be transformed into their absolute equivalents
  using %URI.Base and %URI.MakeAbsolute
! Ruby implemented for XHTML 1.1
! You can now define custom URI filtering behavior, see enduser-uri-filter.html
  for more details
! UTF-8 font names now supported in CSS
- AutoFormatters emit friendly error messages if tags or attributes they
  need are not allowed
- ConfigForm's compactification of directive names is now configurable
- AutoParagraph autoformatter algorithm refined after field-testing
- XHTML 1.1 now applies XHTML 1.0 Strict cleanup routines, namely
  blockquote wrapping
- Contents of <style> tags removed by default when tags are removed
. HTMLPurifier_Config->getSerial() implemented, this is extremely useful
  for output cache invalidation
. ConfigForm printer now can retrieve CSS and JS files as strings, in
  case HTML Purifier's directory is not publically accessible
. Introduce new text/itext configuration directive values: these represent
  longer strings that would be more appropriately edited with a textarea
. Allow newlines to act as separators for lists, hashes, lookups and
  %HTML.Allowed
. ConfigForm generates textareas instead of text inputs for lists, hashes,
  lookups, text and itext fields
. Hidden element content removal genericized: %Core.HiddenElements can
  be used to customize this behavior, by default <script> and <style> are
  hidden
. Added HTMLPURIFIER_PREFIX constant, should be used instead of dirname(__FILE__)
. Custom ChildDef added to default include list
. URIScheme reflection improved: will not attempt to include file if class
  already exists. May clobber autoload, so I need to keep an eye on it
. ConfigSchema heavily optimized, will only collect information and validate
  definitions when HTMLPURIFIER_SCHEMA_STRICT is true.
. AttrDef_URI unit tests and implementation refactored
. benchmarks/ directory now protected from public view with .htaccess file;
  run the tests via command line
. URI scheme is munged off if there is no authority and the scheme is the
  default one
. All unit tests inherit from HTMLPurifier_Harness, not UnitTestCase
. Interface for URIScheme changed
. Generic URI object to hold components of URI added, most systems involved
  in URI validation have been migrated to use it
. Custom filtering for URIs factored out to URIDefinition interface for
  maximum extensibility

2.0.1, released 2007-06-27
! Tag auto-closing now based on a ChildDef heuristic rather than a
  manually set auto_close array; some behavior may change
! Experimental AutoFormat functionality added: auto-paragraph and
  linkify your HTML input by setting %AutoFormat.AutoParagraph and
  %AutoFormat.Linkify to true
! Newlines normalized internally, and then converted back to the
  value of PHP_EOL. If this is not desired, set your newline format
  using %Output.Newline.
! Beta error collection, messages are implemented for the most generic
  cases involving Lexing or Strategies
- Clean up special case code for <script> tags
- Reorder includes for DefinitionCache decorators, fixes a possible
  missing class error
- Fixed bug where manually modified definitions were not saved via cache
  (mostly harmless, except for the fact that it would be a little slower)
- Configuration objects with different serials do not clobber each
  others when revision numbers are unequal
- Improve Serializer DefinitionCache directory permissions checks
- DefinitionCache no longer throws errors when it encounters old
  serial files that do not conform to the current style
- Stray xmlns attributes removed from configuration documentation
- configForm.php smoketest no longer has XSS vulnerability due to
  unescaped print_r output
- Printer adheres to configuration's directives on output format
- Fix improperly named form field in ConfigForm printer
. Rewire some test-cases to swallow errors rather than expect them
. HTMLDefinition printer updated with some of the new attributes
. DefinitionCache keys reordered to reflect precedence: version number,
  hash, then revision number
. %Core.DefinitionCache renamed to %Cache.DefinitionImpl
. Interlinking in configuration documentation added using
  Injector_PurifierLinkify
. Directives now keep track of aliases to themselves
. Error collector now requires a severity to be passed, use PHP's internal
  error constants for this
. HTMLPurifier_Config::getAllowedDirectivesForForm implemented, allows
  much easier selective embedding of configuration values
. Doctype objects now accept public and system DTD identifiers
. %HTML.Doctype is now constrained by specific values, to specify a custom
  doctype use new %HTML.CustomDoctype
. ConfigForm truncates long directives to keep the form small, and does
  not re-output namespaces

2.0.0, released 2007-06-20
# Completely refactored HTMLModuleManager, decentralizing safety
  information
# Transform modules changed to Tidy modules, which offer more flexibility
  and better modularization
# Configuration object now finalizes itself when a read operation is
  performed on it, ensuring that its internal state stays consistent.
  To revert this behavior, you can set the $autoFinalize member variable 
  off, but it's not recommended.
# New compact syntax for AttrDef objects that can be used to instantiate
  new objects via make()
# Definitions (esp. HTMLDefinition) are now cached for a significant
  performance boost. You can disable caching by setting %Core.DefinitionCache
  to null. You CANNOT edit raw definitions without setting the corresponding
  DefinitionID directive (%HTML.DefinitionID for HTMLDefinition).
# Contents between <script> tags are now completely removed if <script>
  is not allowed
# Prototype-declarations for Lexer removed in favor of configuration
  determination of Lexer implementations.
! HTML Purifier now works in PHP 4.3.2.
! Configuration form-editing API makes tweaking HTMLPurifier_Config a
  breeze!
! Configuration directives that accept hashes now allow new string
  format: key1:value1,key2:value2
! ConfigDoc now factored into OOP design
! All deprecated elements now natively supported
! Implement TinyMCE styled whitelist specification format in
  %HTML.Allowed
! Config object gives more friendly error messages when things go wrong
! Advanced API implemented: easy functions for creating elements (addElement)
  and attributes (addAttribute) on HTMLDefinition
! Add native support for required attributes
- Deprecated and removed EnableRedundantUTF8Cleaning. It didn't even work!
- DOMLex will not emit errors when a custom error handler that does not
  honor error_reporting is used
- StrictBlockquote child definition refrains from wrapping whitespace
  in tags now.
- Bug resulting from tag transforms to non-allowed elements fixed
- ChildDef_Custom's regex generation has been improved, removing several
  false positives
. Unit test for ElementDef created, ElementDef behavior modified to
  be more flexible
. Added convenience functions for HTMLModule constructors
. AttrTypes now has accessor functions that should be used instead
  of directly manipulating info
. TagTransform_Center deprecated in favor of generic TagTransform_Simple
. Add extra protection in AttrDef_URI against phantom Schemes
. Doctype object added to HTMLDefinition which describes certain aspects
  of the operational document type
. Lexer is now pre-emptively included, with a conditional include for the
  PHP5 only version.
. HTMLDefinition and CSSDefinition have a common parent class: Definition.
. DirectLex can now track line-numbers
. Preliminary error collector is in place, although no code actually reports
  errors yet
. Factor out most of ValidateAttributes to new AttrValidator class

1.6.1, released 2007-05-05
! Support for more deprecated attributes via transformations:
  + hspace and vspace in img
  + size and noshade in hr
  + nowrap in td
  + clear in br
  + align in caption, table, img and hr
  + type in ul, ol and li
! DirectLex now preserves text in which a < bracket is followed by
  a non-alphanumeric character. This means that certain emoticons
  are now preserved.
! %Core.RemoveInvalidImg is now operational, when set to false invalid
  images will hang around with an empty src
! target attribute in a tag supported, use %Attr.AllowedFrameTargets
  to enable
! CSS property white-space now allows nowrap (supported in all modern
  browsers) but not others (which have spotty browser implementations)
! XHTML 1.1 mode now sort-of works without any fatal errors, and
  lang is now moved over to xml:lang.
! Attribute transformation smoketest available at smoketests/attrTransform.php
! Transformation of font's size attribute now handles super-large numbers
- Possibly fatal bug with __autoload() fixed in module manager
- Invert HTMLModuleManager->addModule() processing order to check
  prefixes first and then the literal module
- Empty strings get converted to empty arrays instead of arrays with
  an empty string in them.
- Merging in attribute lists now works.
. Demo script removed: it has been added to the website's repository
. Basic.php script modified to work out of the box
. Refactor AttrTransform classes to reduce duplication
. AttrTransform_TextAlign axed in favor of a more general
  AttrTransform_EnumToCSS, refer to HTMLModule/TransformToStrict.php to
  see how the new equivalent is implemented
. Unit tests now use exclusively assertIdentical
 
1.6.0, released 2007-04-01
! Support for most common deprecated attributes via transformations:
  + bgcolor in td, th, tr and table
  + border in img
  + name in a and img
  + width in td, th and hr
  + height in td, th
! Support for CSS attribute 'height' added
! Support for rel and rev attributes in a tags added, use %Attr.AllowedRel
  and %Attr.AllowedRev to activate
- You can define ID blacklists using regular expressions via
  %Attr.IDBlacklistRegexp
- Error messages are emitted when you attempt to "allow" elements or
  attributes that HTML Purifier does not support
- Fix segfault in unit test. The problem is not very reproduceable and
  I don't know what causes it, but a six line patch fixed it.

1.5.0, released 2007-03-23
! Added a rudimentary I18N and L10N system modeled off MediaWiki. It
  doesn't actually do anything yet, but keep your eyes peeled.
! docs/enduser-utf8.html explains how to use UTF-8 and HTML Purifier
! Newly structured HTMLDefinition modeled off of XHTML 1.1 modules.
  I am loathe to release beta quality APIs, but this is exactly that;
  don't use the internal interfaces if you're not willing to do migration
  later on.
- Allow 'x' subtag in language codes
- Fixed buggy chameleon-support for ins and del
. Added support for IDREF attributes (i.e. for)
. Renamed HTMLPurifier_AttrDef_Class to HTMLPurifier_AttrDef_Nmtokens
. Removed context variable ParentType, replaced with IsInline, which
  is false when you're not inline and an integer of the parent that
  caused you to become inline when you are (so possibly zero)
. Removed ElementDef->type in favor of ElementDef->descendants_are_inline
  and HTMLDefinition->content_sets
. StrictBlockquote now reports what elements its supposed to allow,
  rather than what it does allow
. Removed HTMLDefinition->info_flow_elements in favor of
  HTMLDefinition->content_sets['Flow']
. Removed redundant "exclusionary" definitions from DTD roster
. StrictBlockquote now requires a construction parameter as if it
  were an Required ChildDef, this is the "real" set of allowed elements
. AttrDef partitioned into HTML, CSS and URI segments
. Modify Youtube filter regexp to be multiline
. Require both PHP5 and DOM extension in order to use DOMLex, fixes
  some edge cases where a DOMDocument class exists in a PHP4 environment
  due to DOM XML extension.

1.4.1, released 2007-01-21
! docs/enduser-youtube.html updated according to new functionality
- YouTube IDs can have underscores and dashes

1.4.0, released 2007-01-21
! Implemented list-style-image, URIs now allowed in list-style
! Implemented background-image, background-repeat, background-attachment
  and background-position CSS properties. Shorthand property background
  supports all of these properties.
! Configuration documentation looks nicer
! Added %Core.EscapeNonASCIICharacters to workaround loss of Unicode
  characters while %Core.Encoding is set to a non-UTF-8 encoding.
! Support for configuration directive aliases added
! Config object can now be instantiated from ini files
! YouTube preservation code added to the core, with two lines of code
  you can add it as a filter to your code. See smoketests/preserveYouTube.php
  for sample code.
! Moved SLOW to docs/enduser-slow.html and added code examples
- Replaced version check with functionality check for DOM (thanks Stephen
  Khoo)
. Added smoketest 'all.php', which loads all other smoketests via frames
. Implemented AttrDef_CSSURI for url(http://google.com) style declarations
. Added convenient single test selector form on test runner

1.3.2, released 2006-12-25
! HTMLPurifier object now accepts configuration arrays, no need to manually
  instantiate a configuration object
! Context object now accessible to outside
! Added enduser-youtube.html, explains how to embed YouTube videos. See
  also corresponding smoketest preserveYouTube.php.
! Added purifyArray(), which takes a list of HTML and purifies it all
! Added static member variable $version to HTML Purifier with PHP-compatible
  version number string.
- Fixed fatal error thrown by upper-cased language attributes
- printDefinition.php: added labels, added better clarification
. HTMLPurifier_Config::create() added, takes mixed variable and converts into
  a HTMLPurifier_Config object.

1.3.1, released 2006-12-06
! Added HTMLPurifier.func.php stub for a convenient function to call the library
- Fixed bug in RemoveInvalidImg code that caused all images to be dropped
  (thanks to .mario for reporting this)
. Standardized all attribute handling variables to attr, made it plural

1.3.0, released 2006-11-26
# Invalid images are now removed, rather than replaced with a dud
  <img src="" alt="Invalid image" />. Previous behavior can be restored
  with new directive %Core.RemoveInvalidImg set to false.
! (X)HTML Strict now supported
  + Transparently handles inline elements in block context (blockquote)
! Added GET method to demo for easier validation, added 50kb max input size
! New directive %HTML.BlockWrapper, for block-ifying inline elements
! New directive %HTML.Parent, allows you to only allow inline content
! New directives %HTML.AllowedElements and %HTML.AllowedAttributes to let
  users narrow the set of allowed tags
! <li value="4"> and <ul start="2"> now allowed in loose mode
! New directives %URI.DisableExternalResources and %URI.DisableResources
! New directive %Attr.DisableURI, which eliminates all hyperlinking
! New directive %URI.Munge, munges URI so you can use some sort of redirector
  service to avoid PageRank leaks or warn users that they are exiting your site.
! Added spiffy new smoketest printDefinition.php, which lets you twiddle with
  the configuration settings and see how the internal rules are affected.
! New directive %URI.HostBlacklist for blocking links to bad hosts.
  xssAttacks.php smoketest updated accordingly.
- Added missing type to ChildDef_Chameleon
- Remove Tidy option from demo if there is not Tidy available
. ChildDef_Required guards against empty tags
. Lookup table HTMLDefinition->info_flow_elements added
. Added peace-of-mind variable initialization to Strategy_FixNesting
. Added HTMLPurifier->info_parent_def, parent child processing made special
. Added internal documents briefly summarizing future progression of HTML
. HTMLPurifier_Config->getBatch($namespace) added
. More lenient casting to bool from string in HTMLPurifier_ConfigSchema
. Refactored ChildDef classes into their own files

1.2.0, released 2006-11-19
# ID attributes now disabled by default. New directives:
  + %HTML.EnableAttrID - restores old behavior by allowing IDs
  + %Attr.IDPrefix - %Attr.IDBlacklist alternative that munges all user IDs
    so that they don't collide with your IDs
  + %Attr.IDPrefixLocal - Same as above, but for when there are multiple
    instances of user content on the page
  + Profuse documentation on how to use these available in docs/enduser-id.txt
! Added MODx plugin <http://modxcms.com/forums/index.php/topic,6604.0.html>
! Added percent encoding normalization
! XSS attacks smoketest given facelift
! Configuration documentation now has table of contents
! Added %URI.DisableExternal, which prevents links to external websites.  You
  can also use %URI.Host to permit absolute linking to subdomains
! Non-accessible resources (ex. mailto) blocked from embedded URIs (img src)
- Type variable in HTMLDefinition was not being set properly, fixed
- Documentation updated
  + TODO added request Phalanger
  + TODO added request Native compression
  + TODO added request Remove redundant tags
  + TODO added possible plaintext formatter for HTML Purifier documentation
  + Updated ConfigDoc TODO
  + Improved inline comments in AttrDef/Class.php, AttrDef/CSS.php
    and AttrDef/Host.php
  + Revamped documentation into HTML, along with misc updates
- HTMLPurifier_Context doesn't throw a variable reference error if you attempt
  to retrieve a non-existent variable
. Switched to purify()-wide Context object registry
. Refactored unit tests to minimize duplication
. XSS attack sheet updated
. configdoc.xml now has xml:space attached to default value nodes
. Allow configuration directives to permit null values
. Cleaned up test-cases to remove unnecessary swallowErrors()

1.1.2, released 2006-09-30
! Add HTMLPurifier.auto.php stub file that configures include_path
- Documentation updated
  + INSTALL document rewritten
  + TODO added semi-lossy conversion
  + API Doxygen docs' file exclusions updated
  + Added notes on HTML versus XML attribute whitespace handling
  + Noted that HTMLPurifier_ChildDef_Custom isn't being used
  + Noted that config object's definitions are cached versions
- Fixed lack of attribute parsing in HTMLPurifier_Lexer_PEARSax3
- ftp:// URIs now have their typecodes checked
- Hooked up HTMLPurifier_ChildDef_Custom's unit tests (they weren't being run)
. Line endings standardized throughout project (svn:eol-style standardized)
. Refactored parseData() to general Lexer class
. Tester named "HTML Purifier" not "HTMLPurifier"

1.1.1, released 2006-09-24
! Configuration option to optionally Tidy up output for indentation to make up
  for dropped whitespace by DOMLex (pretty-printing for the entire application
  should be done by a page-wide Tidy)
- Various documentation updates
- Fixed parse error in configuration documentation script
- Fixed fatal error in benchmark scripts, slightly augmented
- As far as possible, whitespace is preserved in-between table children
- Sample test-settings.php file included

1.1.0, released 2006-09-16
! Directive documentation generation using XSLT
! XHTML can now be turned off, output becomes <br>
- Made URI validator more forgiving: will ignore leading and trailing
  quotes, apostrophes and less than or greater than signs.
- Enforce alphanumeric namespace and directive names for configuration.
- Table child definition made more flexible, will fix up poorly ordered elements
. Renamed ConfigDef to ConfigSchema

1.0.1, released 2006-09-04
- Fixed slight bug in DOMLex attribute parsing
- Fixed rejection of case-insensitive configuration values when there is a
  set of allowed values.  This manifested in %Core.Encoding.
- Fixed rejection of inline style declarations that had lots of extra
  space in them.  This manifested in TinyMCE.

1.0.0, released 2006-09-01
! Shorthand CSS properties implemented: font, border, background, list-style
! Basic color keywords translated into hexadecimal values
! Table CSS properties implemented
! Support for charsets other than UTF-8 (defined by iconv)
! Malformed UTF-8 and non-SGML character detection and cleaning implemented
- Fixed broken numeric entity conversion
- API documentation completed
. (HTML|CSS)Definition de-singleton-ized

1.0.0beta, released 2006-08-16
! First public release, most functionality implemented. Notable omissions are:
  + Shorthand CSS properties
  + Table CSS properties
  + Deprecated attribute transformations