---
appendix: A
title: Modifications
---
## Unicode Technical Standard #35

# Unicode Locale Data Markup Language (LDML)<br/>Appendix A: Modifications

For the full header, table of contents, and status, see [Part 1: Core](tr35.md).

### _Summary_

This is a partial document, describing only the changes to the LDML since the previous release. For the other parts of the LDML see the [main LDML document](tr35.md).

## <a name="Contents" href="#Contents">Contents of Appendix A, Modifications</a>

* [Modifications](#modifications)
  * [MessageFormat](#messageformat)
  * [Locale Identifiers and Names](#locale-identifiers-and-names)
  * [Misc.](#misc)
  * [DateTime formats](#datetime-formats)
  * [Numbers](#numbers)
  * [Units of Measurement](#units-of-measurement)
  * [Collation](#collation)
  * [MessageFormat](#messageformat)
  * [Keyboards](#keyboards)
  * [Modifications section](#modifications-section)
  * [Acknowledgments section](#acknowledgments-section)

## Modifications

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**Changes in LDML Version 49 (Differences from Version 48.2)**

* [Calendar era `code`s](tr35-dates.md#Calendar_Data) Added length limit
<!-- CLDR-5717 updated some example -->

* [`typeValues`](tr35-general.md#type-values) Added typeValues for On/Off translations
<!-- CLDR-19394 -->

* [`numberFormat`](tr35-numbers.md#Number_Formats) Revise numberFormat description
<!-- CLDR-18963 -->

* [`dateTime`](tr35-dates.md#Time_Zone_Names) Removed `gmtZeroOffset` item


**Changes in LDML Version 48.2 (Differences from Version 48.1)**

<!-- CLDR-19231 reformatted/simplified tr35.md version block to improve deployment-->

* New section [Nested Bracket Replacement](tr35-general.md#Character_Nested_Bracket_Replacement)
* [Locale Display Name Algorithm](tr35-general.md#locale_display_name_algorithm) updated to use the nested bracket replacement data and avoid nested parentheses by flattening `-t-` (transform) language names.
    * As part of this, the display name order is changed so that any names for `-u-` items appear _before_ (instead of after) any names for `-t-` items.
* Specify that missing `<keys>` translations should fall back to the key identifier
* The section "Enhanced Language Matching" is retitled as [Language Matching Variables](tr35.md#enhanced-language-matching) and clarified.

**Changes in LDML Version 49 (Differences from Version 48.2)**
* Clarified the process of selecting the best `dateFormatItem` when there is no exact match, and how to use `appendItems` to add missing fields. This includes a clarification of what are date fields and what are time fields, and a note that `appendItems` for date and time fields should be appended before combining them.
<!-- Updated spec date -->

### MessageFormat

* The `:currency` and `:percent` functions are now Stable, with the same implementations as previously.
* The `u:locale` option (previously in Draft) is dropped from the specification.

**Changes in LDML Version 48.1 (Differences from Version 48)**

* [Segmentations](tr35-general.md#Segmentations) removed outdated note about `X Format*->X` not being supported in CLDR since it no longer accurate.

**Changes in LDML Version 48 (Differences from Version 47)**

### Locale Identifiers and Names
* [Display Name Elements](tr35-general.md#display-name-elements) Described the usage of the `language` element `menu` values `core` and `extension`, and `alt="menu"`.
Also revamped the description of how to construct names for locale IDs, for clarity.
* [Special Script Codes](tr35.md#special-script-codes) Added the `Hntl` compound script. (This is also reflected in the `<scriptData>` elements in supplementalData.xml.)
* [Likely Subtags](tr35.md#likely-subtags) Changed the Canonicalize step to point to the section on canonicalization.
* [Unicode Locale Identifier](tr35.md#unicode-locale-identifier) Changed the `attribute` component in the EBNF to be `uattribute` for consistency with `ufield`, etc.
and to reduce confusion with XML attributes.
* [Unicode Subdivision Codes](tr35.md#Unicode_Subdivision_Codes) Added more
explanation about the potential reuse of ISO 3166-2 codes, and clarified that
CLDR does not closely monitor all ISO 3166-2 changes.

### Misc.
* [Character Elements](tr35-general.md#character-elements) Added new exemplar types.
* [DTD Annotations](tr35.md#DTD_Annotations) Added the @CDATA annotation, to indicate which elements are generated with @CDATA format
* [Person Name Validation](tr35-personNames.md#person-name-validation) Added guidance for validating person names.
* [Supplemental Language Data](tr35-info.md#Supplemental_Language_Data) For the `language` subelement of `languageData`, the `territory`
attribute has been deprecated (and data using it has been removed). A better source for such information is the more detailed data
in [Supplemental Territory Information](tr35-info.md#Supplemental_Territory_Information).

### DateTime formats

* [Element dateTimeFormat](tr35-dates.md#dateTimeFormat) Added a new type `relative` for relative date/times, such as "tomorrow at 10:00",
and updated the guidelines for using the different `dateTimeFormat` types.
* [Using Time Zone Names](tr35-dates.md#using-time-zone-names) Removed the "specific location format".
* [timeZoneNames Elements Used for Fallback](tr35-dates.md#timeZoneNames_Elements_Used_for_Fallback) Added the `gmtUnknownFormat`, to indicate when the timezone is unknown.
* [Metazone Names](tr35-dates.md#metazone-names) Added `usesMetazone`, to specify which offset is considered standard time, and which offset is considered daylight.
* [Time Zone Format Terminology](tr35-dates.md#time-zone-format-terminology) Added the **Localized GMT format** (replacing the **Specific location format**).
This affects the behavior of the `z` timezone format symbol.
There is also now a mechanism for finding the region code from short timezone identifier, which is used for the _non-location formats (generic or specific)_
* [Calendar Data](tr35-dates.md#calendar-data) Specified more precisely the meaning of the `era` attributes in supplemental data, and how to determine the transition point in time between eras.

### Numbers
* [Plural rules syntax](tr35-numbers.md#plural-rules-syntax) Added substantial clarifications and new examples.
The order of execution is also clearly specified.
* [Compact Number Formats](tr35-numbers.md#compact-number-formats) Specified the mechanism for formatting compact numbers more precisely.
* [Rule-Based Number Formatting](tr35-numbers.md#) Added a full specification.
The rules have been converted to a “flat” format, which is easier for clients to handle (the old format will be retained for one more release).
* [Rational Numbers](tr35-numbers.md#rational-numbers) Added support for formatting fractions like 5½ in technical preview.

### Units of Measurement
* [Unit Syntax](tr35-general.md#unit-syntax) Simplified the EBNF `product_unit` and added an additional well-formedness constraint for mixed units.
* [Unit Identifier Normalization](tr35-info.md#Unit_Identifier_Normalization) Modified the normalization process
* [Mixed Units](tr35-general.md#Unit_Sequences) Modified the guidance for handling precision.

### Collation
* [Collation](tr35-collation.md) Added the new `FractionalUCA_blanked.txt` to the root collation data files.

### MessageFormat
* Syntax and data model errors must now be prioritized over other errors <!-- ([\#1011](https://github.com/unicode-org/message-format-wg/pull/1011)) -->
* The Default Bidi Strategy is now required and default <!-- ([\#1066](https://github.com/unicode-org/message-format-wg/pull/1066)) -->
* The `:offset` function (previously named `:math`) is now available as Stable <!-- ([\#1073](https://github.com/unicode-org/message-format-wg/pull/1073)) -->
* The `:datetime`, `:date`, and `:time` _draft_ functions are updated to build on top of semantic skeletons <!-- ([\#1078](https://github.com/unicode-org/message-format-wg/pull/1078), [\#1083](https://github.com/unicode-org/message-format-wg/pull/1083)) -->
* `:percent` is added as a new _draft_ function <!-- ([\#1094](https://github.com/unicode-org/message-format-wg/pull/1094)) -->
* The format is renamed to "Unicode MessageFormat" for clarity <!-- ([\#1064](https://github.com/unicode-org/message-format-wg/pull/1064)) -->
* The pattern selection definition is refactored to be easier to understand without changing its meaning <!-- ([\#1080](https://github.com/unicode-org/message-format-wg/pull/1080)) -->

### Keyboards

* [`display`](tr35-keyboards.md#element-display): Noted that a key without output may be indicated by means of the `keyId=` attribute on the display.
* [`layer`](tr35-keyboards.md#element-layer): Noted the use of the `modifiers=` attribute for hardware layouts being used as touch layouts.
* References and links into the section concerning keyboard test data (which was removed prior to spec finalization) were removed.
* Normalization for the default backspace transform was clarified, and authors were encouraged to add backspace transforms to avoid the default.

### Modifications section

* The Modifications section was split out to its own file, [Appendix A, Modifications](tr35-modifications.md)

### Acknowledgments section

* The Acknowledgments section was split out to its own file, [Appendix B, Acknowledgments](tr35-acknowledgments.md)

Note that small changes such as typos and link fixes are not listed above.
Modifications in previous versions are listed in those respective versions.
Click on **Previous Version** in the header until you get to the desired version.

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