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* Create notes-2024-08-19.md

* Accept attributes design & remove spec note (#845)

* Accept attributes design & remove spec note

* Disallow duplicate attribute names (closes #756)

* Add link to contextual options PR

* Add more prose to tag example text

Co-authored-by: Addison Phillips <addison@unicode.org>

* Mention attribute validity condition in the **_valid_** definition

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Update selection-declaration design doc based on mtg / issue discussion (#867)

* Add tests for pattern selection (#863)

* Add tests for pattern selection

* Add missing errors

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Add Duplicate Variant to table in test/README.md (#861)

* Add new selection-declaration alternative: Require annotation of selector variables in placeholders (#860)

* Add new selection-declaration alternative: Require annotation of selector variables in placeholders

* Improve examples

* Switch example order

* Update the stability policy (#834)

* Update the stability policy

Based on discussion in the 2024-07-22 call and in PR #829, update the stability policy.

* A deeper, more thorough rewrite

- Standardizes the phrasing completely.
- Moves all potential future changes (which are not, after all, stability policies) to an "important" block
- Removes duplication
- Separates functions, options, and option values into separate guarantees
- Clarifies the note about formatting changing over time

* Update spec/README.md

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Update spec/README.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* remove well-formed

* Update spec/README.md

---------

Co-authored-by: Tim Chevalier <tjc@igalia.com>
Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Refine error handling text (#816)

* Refine error handling text

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Update fallback text

* Turn bullet point list into paragraphs

* Be more mighty

Co-authored-by: Addison Phillips <addison@unicode.org>

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Create notes-2024-08-26.md

* Select "Match on variables instead of expressions" for selection-declarations (#824)

* Select "Match on variables instead of expressions" for selection-declarations

* Add hybrid option to selection-declaration.md (#870)

* Add hybrid option to selection-declaration.md

* Update selection-declaration.md

fixed glitch in original edit

* Update selection-declaration.md

* Apply suggestions from code review

Fixing typos

Co-authored-by: Addison Phillips <addison@unicode.org>

* Update selection-declaration.md

* Update exploration/selection-declaration.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update exploration/selection-declaration.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update exploration/selection-declaration.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

---------

Co-authored-by: Addison Phillips <addison@unicode.org>
Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update selection-declaration.md

---------

Co-authored-by: Mark Davis <mark@unicode.org>
Co-authored-by: Addison Phillips <addison@unicode.org>

* Fix "Allow immutable input declarative selectors" example (#874)

* Update README.md (#875)

* Update README.md

* Update README.md

* [DESIGN] Update bidi design document to show proposed design (#871)

* [DESIGN] Update bidi design document to show proposed design

The design I actually think we should adopt is the "hybrid approaches" one. This is a necessary first step on the highway to UAX31 compliance and I think is responsibly contained/managed. It is a hybrid approach, in that it permits testable strict implementations to be created (particularly for message serialization).

This PR consists of moving text around. I added one "pro" to one option also.

* Address comments

* Miscellaneous test fixes (#862)

* Add missing expected bad-selector errors

* Fix expected parts for unsupported-statement test

* Add a few new tests for leading-whitespace and duplicate-variant

* Add tests for escaped-char changes made in #743

* Fix tests for attributes with variable values

* Update contributing and joining info (#876)

* Update contributing and joining info

* Update README.md

* Update CONTRIBUTING.md

* Restore CLA copy

* Clarify error & fallback handling (#879)

* Clarify error & fallback handling

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Select last rather than first attribute

* Drop mention of "starting with Pattern Selection"

* Attributes can't change the formatted output

* Use "nor" instead of "or" regarding attribute restrictions

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Clarify rule selection (#878)

* Clarify rule selection

Fixes #868 

This adds normative SHOULD language to using CLDR plural and ordinal data, which was intended originally.

- clarifies that keyword selection follows exact match
- clarifies the purpose of rule-based selection
- makes non-CLDR-based implementation permitted

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

---------

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* [DESIGN] Maintaining the Standard, Optional and Unicode Namespace Function Sets (#634)

* Design doc to capture registry maintenance

* Update maintaining-registry.md

* Update exploration/maintaining-registry.md

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Update exploration/maintaining-registry.md

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Add user stories, small updates to RGI

* Update exploration/maintaining-registry.md

* Adding additional detail

* Remove machine readable registry; update prose

* Update maintaining-registry.md

* Further development work

* Update to change format and naming

Per the 2024-08-19 call, we decided to switch towards a specification-per-function model, with statuses. This commit includes the initial set of changes to try and implement this.

* Address some comments.

---------

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Create notes-2024-09-09.md

* Fix a typo in an example (#880)

The upcoming work to implement resolved value might make this patch unnecessary or obsolete, but fixing the typo (missing `{`/`}` around the variable in the pattern) just in case

* Remove forward-compatibility promise and all reserved & private syntax (#883)

* Remove forwards compatibility from stability guarantee

* Drop reserved statements and expressions

* Drop private-use annotations

* Update tests

* Clarify that deprecation is not removal

* Match on variables instead of expressions (#877)

* Match on variables instead of expressions

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Apply suggestions from code review

* Add missing test changes noticed during implementation

* Empty commit to re-trigger CLA check

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Create notes-2024-09-10.md

* Add bidi support and address UAX31/UTS55 requirements (#884)

* Add bidi support and address UAX31/UTS55 requirements

Adds the bidi strong marks ALM, RLM, and LRM plus the bidi isolate controls LRI, RLI, FSI, and PDI to the syntax.

Formally defines optional vs. non-optional whitespace.

Non-optional whitespace must include at least one whitespace character. Optional whitespace may contain only bidi marks (which are invisible)

* Update syntax.md including text from previous PR

* Repair the guidance on strongly directional marks

Include ALM and better specify how to use the marks.

* Fix formatting of the "important"

* Add bidi characters to description of whitespace.

* Permit bidi in a few more places

Add optional whitespace at the start of `variant`

Add optional whitespace around `quoted-pattern`

These changes result in allowing bidi around keys and quoted patterns as intended.

* Update syntax.md ABNF

* Update formatting.md

- Add a note about the difference between formatting and message syntax.
- Clarify the sentence about message directionality.

* Address comment about name/identifier

* Address comments related to bidi in `name`

* Fix variable's location

* Address comment about the list of LRI/PDI targets

* One character typo :-P

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Address comments about rule R3a-1

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Address comment about U+061C

* Change [o]wsp => `o` or `s`

* Match syntax spec to abnf

* Remove *

* Update syntax.md

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/message.abnf

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/message.abnf

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update syntax.md

* Update spec/message.abnf

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

---------

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Specify `bad-option` for bad digit size option values (#882)

* Specify `bad-option` for bad digit size option values

Fixes #739

* adopt 'non-negative integer'

* Create notes-2024-09-16.md

* Address name and literal equality (#885)

* Address name and literal equality

This change defines equality as discussed in the 2024-09-09 teleconference in the following ways:

- It defines _name_ equality as being under NFC
- It defines _literal_ equality as explicitly **not** under NFC
- It moves _name_ before _identifier_ in that section of text to avoid a forward definition.

Note that this deviates from discussion in 2024-09-09's call in that we didn't discuss literals at length. It also doesn't discuss non-name/non-literal values, which I'll point out are limited to ASCII sequences such as keywords.

* Typo fix

* Add a note about not requiring implementations to actually normalize

* Implement changes dicussed in 2024-09-16 call.

- Make _key_ require NFC for uniqueness/comparison
- Add a note about NFC
- Make _literal_ **_not_** define equality
- Make text in _name_ identical to that in _key_ for consistency

* Update formatting.md to include keys in NFC

* Address comments

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/syntax.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

---------

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update list of normative changes during the LDML45 period (#890)

* Fix typos in data-model-errors tests (#892)

Fix #886

* Update note on exact numeric match for v46 (#891)

Addresses #887 

Non-normative changes to the notes specifically part of LDML46

* Fix attribute value to be literal (#894)

Fixes #893

* Create notes-2024-09-30.md

* Add Resolved Values and Function Handler sections to formatting (#728)

* Add Resolved Values section to formatting

* Apply suggestions from code review

* Apply suggestions from code review

* Apply suggestions from code review

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Linkify "resolved value"

* Add some examples & explicitly allow wrapping input values

* No throw, only emit

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Add section on Function Handlers, defining the term

* Apply suggestions from code review

* Rephrase initial resolved value definition

* Update spec/formatting.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update resolved value definition again

Co-authored-by: Addison Phillips <addison@unicode.org>

---------

Co-authored-by: Tim Chevalier <tjc@igalia.com>
Co-authored-by: Addison Phillips <addison@unicode.org>

* Define function composition for :number and :integer values (#823)

* Define function composition for :number and :integer values

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Add operand option priority example

* Add apostrophes'

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

---------

Co-authored-by: Addison Phillips <addison@unicode.org>
Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Create notes-2024-10-07.md

* Apply NFC normalization during :string key comparison (#905)

* Apply NFC normalization during :string key comparison

* Add link to UAX#15

Co-authored-by: Addison Phillips <addison@unicode.org>

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Add tests for changes due to bidi/whitespace (#902)

* Add tests for changes due to bidi/whitespace

* Correct output

* Make erroneous test a syntax error

* Define function composition for date/time values (#814)

* Define function composition for date/time values

* Apply suggestions from code review

Co-authored-by: Stanisław Małolepszy <sta@malolepszy.org>

* Drop the "only"

* Update spec/registry.md

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Update spec/registry.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Make :date and :time composition implementation-defined

---------

Co-authored-by: Stanisław Małolepszy <sta@malolepszy.org>
Co-authored-by: Addison Phillips <addison@unicode.org>

* DESIGN: Add alternative designs to the design doc on function composition (#806)

* DESIGN: Add a sequel to the design doc on function composition

This document sketches out some alternatives for the machinery
provided to enable function composition.

The goal is to provide an exhaustive list of alternatives.

* Remove 'part 2' document and move contents to the end of part 1

* Revise introduction to reflect the changed goal

* Edited for conciseness

* Further edits for conciseness

* Give a name to InputType and use it

* Refer to motivating examples

* Update function-composition-part-1.md status

Per 2024-10-14 telecon

* Create notes-2024-10-14.md

* Add test for :integer and :number composition (#907)

* Fix `:integer` option `useGrouping` values (#912)

I noticed that `:integer` does not include the "never" value for the option `useGrouping`. This is a bug.

* Drop syntax note on additional bidi changes (#910)

Drop syntax note on addition bidi changes

* Add tests for changes due to #885 (name/literal equality) (#904)

* Add tests for changes due to #885 (name/literal equality)

* Update test/tests/functions/string.json

Co-authored-by: Eemeli Aro <eemeli@gmail.com>

* Update test/tests/syntax.json

Co-authored-by: Eemeli Aro <eemeli@gmail.com>

* Update test/tests/functions/string.json

Co-authored-by: Eemeli Aro <eemeli@gmail.com>

* Added tests for reordering and special case mapping

* Add another selection test

---------

Co-authored-by: Eemeli Aro <eemeli@gmail.com>

* Add u: options namespace (#846)

* Move spec/registry.md -> spec/registry/default.md

* Add Unicode Registry definition

* Refer to BCP47, add note about only requiring normal tags

* Call it a namespace

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Fix test file reference

Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Apply suggestions from code review

* Update spec/u-namespace.md

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Apply suggestions from code review

Co-authored-by: Addison Phillips <addison@unicode.org>

* Add mention of functions to namespace description

---------

Co-authored-by: Addison Phillips <addison@unicode.org>
Co-authored-by: Tim Chevalier <tjc@igalia.com>

* Define function composition for :string values (#798)

* Define function composition for :string values

* Update spec/registry.md as suggested by @stasm in #814

* Drop the "only"

* Update text following code review comments

---------

Co-authored-by: Addison Phillips <addison@unicode.org>

* Drop data model request for feedback on "name" (#909)

* Allow surrogates in content, issue #895 (#906)

* Allow surrogates in content, issue #895

* Grammar and typos, linkify terms, make into a note, and fix 2119 keywords

Thanks Addison!

Co-authored-by: Addison Phillips <addisonI18N@gmail.com>

* Not using "localizable elements"

Co-authored-by: Addison Phillips <addisonI18N@gmail.com>

* Keep syntax.md in sync with message.abnf

* Added note about surrogates to quoted literals

* Moved the note about surrogates from Security Considerations to The Message

* Update spec/syntax.md

* Update spec/syntax.md

* Italicize  in a couple of places

* Implemeted more (all?) feedback from review

---------

Co-authored-by: Addison Phillips <addisonI18N@gmail.com>

---------

Co-authored-by: Eemeli Aro <eemeli@mozilla.com>
Co-authored-by: Elango Cheran <elango@unicode.org>
Co-authored-by: Tim Chevalier <tjc@igalia.com>
Co-authored-by: Mark Davis <mark@unicode.org>
Co-authored-by: Danny Gleckler <daniel.gleckler@d2l.com>
Co-authored-by: Steven R. Loomis <srl295@gmail.com>
Co-authored-by: Stanisław Małolepszy <sta@malolepszy.org>
Co-authored-by: Eemeli Aro <eemeli@gmail.com>
Co-authored-by: Mihai Nita <nmihai_2000@yahoo.com>
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9 changes: 1 addition & 8 deletions CONTRIBUTING.md
Original file line number Diff line number Diff line change
@@ -1,13 +1,6 @@
# Contributing to this project

## Joining the Working Group

We are looking for participation from software developers, localization engineers and others with experience
in Internationalization (I18N) and Localization (L10N). If you wish to contribute to this work, please review
the information on the Contributor License Agreement below. In addition, you should:

1. Apply to join our [mailing list](https://groups.google.com/a/chromium.org/forum/#!forum/message-format-wg)
2. Watch this repository (use the "Watch" button in the upper right corner)
To join this Working Group, please read the information in the [README.md](./README.md) as well as the Contributor License Agreement information just below:

<!-- boilerplate follows - do not edit -->

Expand Down
47 changes: 38 additions & 9 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,8 @@ Functions can optionally take _options_:
Messages can use a _selector_ to choose between different _variants_,
which correspond to the grammatical (or other) requirements of the language:

.match {$count :integer}
.input {$count :integer}
.match $count
0 {{You have no notifications.}}
one {{You have {$count} notification.}}
* {{You have {$count} notifications.}}
Expand Down Expand Up @@ -105,6 +106,23 @@ The `main` branch of this repository contains changes implemented since the tech
Implementers should be aware of the following normative changes during the tech preview period.
See the [commit history](https://github.com/unicode-org/message-format-wg/commits)
after 2024-04-13 for a list of all commits (including non-normative changes).
- [#885](https://github.com/unicode-org/message-format-wg/issues/885) Address equality of `name` and `literal` values, including requiring keys to use NFC
- [#884](https://github.com/unicode-org/message-format-wg/issues/884) Add support for bidirectional isolates and strong marks in syntax and address UAX31/UTS55 requirements
- [#883](https://github.com/unicode-org/message-format-wg/issues/883) Remove forward-compatibility promise and all reserved/private syntax.
- [#882](https://github.com/unicode-org/message-format-wg/issues/882) Specify `bad-option` error for bad digit size options in `:number` and `:integer` functions
- [#878](https://github.com/unicode-org/message-format-wg/issues/878) Clarify "rule" selection in `:number` and `:integer` functions
- [#877](https://github.com/unicode-org/message-format-wg/issues/877) Match on variables instead of expressions.
- [#854](https://github.com/unicode-org/message-format-wg/issues/854) Allow whitespace at complex message start
- [#853](https://github.com/unicode-org/message-format-wg/issues/853) Add a "duplicate-variant" error
- [#845](https://github.com/unicode-org/message-format-wg/issues/845) Define "attributes" feature
- [#834](https://github.com/unicode-org/message-format-wg/issues/834) Modify the stability policy (not currently in effect due to Tech Preview)
- [#816](https://github.com/unicode-org/message-format-wg/issues/816) Refine error handling
- [#815](https://github.com/unicode-org/message-format-wg/issues/815) Removed machine-readable function registry as a deliverable
- [#813](https://github.com/unicode-org/message-format-wg/issues/813) Change default of `:date` and `:datetime` date formatting from `short` to `medium`
- [#812](https://github.com/unicode-org/message-format-wg/issues/812) Allow trailing whitespace for complex messages
- [#793](https://github.com/unicode-org/message-format-wg/issues/793) Recommend the use of escapes only when necessary
- [#775](https://github.com/unicode-org/message-format-wg/issues/775) Add formal definitions for variable, external variable, and local variable
- [#774](https://github.com/unicode-org/message-format-wg/issues/774) Refactor errors, adding Message Function Errors
- [#771](https://github.com/unicode-org/message-format-wg/issues/771) Remove inappropriate normative statement from errors.md
- [#767](https://github.com/unicode-org/message-format-wg/issues/767) Add a test schema and
[#778](https://github.com/unicode-org/message-format-wg/issues/778) validate tests against it
Expand All @@ -113,7 +131,9 @@ after 2024-04-13 for a list of all commits (including non-normative changes).
- [#769](https://github.com/unicode-org/message-format-wg/issues/769) Add `:test:function`,
`:test:select` and `:test:format` functions for implementation testing
- [#743](https://github.com/unicode-org/message-format-wg/issues/743) Collapse all escape sequence rules into one (affects the ABNF)
- _more to be added as they are merged_

In addition to the above, the test suite is significantly modified and updated.


## Implementations

Expand All @@ -137,18 +157,27 @@ We invite feedback about the current syntax draft, as well as the real-life use-
- General questions and thoughts → [post a discussion thread](https://github.com/unicode-org/message-format-wg/discussions).
- Actionable feedback (bugs, feature requests) → [file a new issue](https://github.com/unicode-org/message-format-wg/issues).

## Participation
## Participation / Joining the Working Group

We are looking for participation from software developers, localization engineers and others with experience
in Internationalization (I18N) and Localization (L10N).
If you wish to contribute to this work, please review the information about the Contributor License Agreement below.

To join in:
To follow this work:
1. Apply to join our [mailing list](https://groups.google.com/a/chromium.org/forum/#!forum/message-format-wg)
2. Watch this repository (use the "Watch" button in the upper right corner)

1. Review [CONTRIBUTING.md](./CONTRIBUTING.md)
2. Apply to join our [mailing list](https://groups.google.com/a/chromium.org/forum/#!forum/message-format-wg)
3. Watch this repository (use the "Watch" button in the upper right corner)
To contribute to this work, in addition to the above:
1. Each individual MUST have a copy of the CLA on file. See below.
2. Individuals who are employees of Unicode Member organizations SHOULD contact their member representative.
Individuals who are not employees of Unicode Member organizations MUST contact the chair to request Invited Expert status.
Employees of Unicode Member organizations MAY also apply for Invited Expert status,
subject to approval from their member representative.

### Copyright & Licenses

Copyright © 2019-2024 Unicode, Inc. Unicode and the Unicode Logo are registered trademarks of Unicode, Inc. in the United States and other countries.

The project is released under [LICENSE](./LICENSE).

A CLA is required to contribute to this project - please refer to the [CONTRIBUTING.md](./CONTRIBUTING.md) file (or start a Pull Request) for more information.

The contents of this repository are governed by the Unicode [Terms of Use](https://www.unicode.org/copyright.html) and are released under [LICENSE](./LICENSE).
71 changes: 49 additions & 22 deletions exploration/bidi-usability.md
Original file line number Diff line number Diff line change
Expand Up @@ -273,6 +273,39 @@ Not allowing these to mix could produce annoying parse errors.

_Describe the proposed solution. Consider syntax, formatting, errors, registry, tooling, interchange._

I propose adopting a hybrid approach in which we permit "super-loose isolation".
This allows user to include isolates and strongly directional characters into the whitespace
portions of the syntax in order to make messages appear correctly.

The second part of the hybrid approach would be to recommend ("SHOULD") the "strict isolation"
design for serializers.
(Note that "strict" and "super-loose" use non-identical productions with the name `bidi`.
These serve different purposes and are consistent with strict being narrower with super-loose.)
This syntax is a subset of the super-loose syntax and can be applied selectively to messages that
have RTL sequences or which have problematic display.


## Alternatives Considered

_What other solutions are available?_
_How do they compare against the requirements?_
_What other properties they have?_

### Nothing
We could do nothing.

A likely outcome of doing nothing is that RTL users would insert bidi controls into
_messages_ in an attempt to make the _pattern_ and/or _placeholders_ display correctly.
These controls would become part of the output of the _message_,
showing up inappropriately at runtime.
Because these characters are invisible, users might be very frustrated trying to manage
the results or debug what is wrong with their messages.

By contrast, if users insert too many or the wrong controls using the recommended design,
the _message_ would still be functional and would emit no undesired characters.

### LTR Messages with isolating sequences

The syntax of a _message_ assumes a left-to-right base direction
both for the complete text of the _message_ as well as for each line (paragraph)
contained therein.
Expand Down Expand Up @@ -383,7 +416,7 @@ ns-separator = [bidi] ":"
bidi = [ %x200E-200F / %x061C ]
```

### Open Issues with Proposed Design
**Open Issues**

The ABNF changes found above put isolates and strongly directional marks into specific locations,
such as directly next to `{`/`}`/`{{`/`}}` markers
Expand All @@ -393,32 +426,24 @@ A more permissive design would add the isolates and strongly directional marks t
whitespace in the syntax and depend on users/editors to appropriately pair or position the marks
to get optimal display.

## Alternatives Considered

_What other solutions are available?_
_How do they compare against the requirements?_
_What other properties they have?_

### Nothing
We could do nothing.

A likely outcome of doing nothing is that RTL users would insert bidi controls into
_messages_ in an attempt to make the _pattern_ and/or _placeholders_ display correctly.
These controls would become part of the output of the _message_,
showing up inappropriately at runtime.
Because these characters are invisible, users might be very frustrated trying to manage
the results or debug what is wrong with their messages.

By contrast, if users insert too many or the wrong controls using the recommended design,
the _message_ would still be functional and would emit no undesired characters.

### Super-loose isolation

Add isolates and strongly directional marks to required and optional whitespace in the syntax.
This would permit users to get the effects described by the above design,
as long as they use isolates/marks in a "responsible" way.

(Omitting other changes found in #673)
The exception to this is the namespace separator, used in `identifier`.
This requires the ability to insert isolates or strongly directional marks
between the namespace and name portions, where whitespace is not permitted.
This is the only location in the syntax where such characters might be needed
but whitespace is not at least optional.
This could be defined as:
```abnf
ns-separator = [bidi] ":" [bidi]
```

Here are the other ABNF changes:

```abnf
; strongly directional marks and bidi isolates
Expand Down Expand Up @@ -447,7 +472,7 @@ s = ( SP / HTAB / CR / LF / %x3000 )
### Strict isolation all the time

Apply bidi isolates in a strict way.
The main differences to the proposed solution is:
In this design:
1. The open/close isolate characters are syntactically required to be paired.
This introduces parse errors for unpaired invisible characters,
which could lead to bad user experiences.
Expand All @@ -467,7 +492,7 @@ markup = "{" [s] "#" identifier [bidi] *(s option) *(s attribute) [s] ["
/ "{" [s] "/" identifier [bidi] *(s option) *(s attribute) [s] "}" ; close
/ "{" LRI [s] "/" identifier [bidi] *(s option) *(s attribute) [s] close-isolate "}" ; close
identifier = [(namespace ns-separator)] name
ns-separator = [bidi] ":"
ns-separator = [bidi] ":" [bidi]
bidi = [ %x200E-200F / %x061C ]
```

Expand Down Expand Up @@ -610,6 +635,8 @@ adherence to the stricter grammar.
syntax errors
- Provides a foundation for tools to claim strict conformance and message normalization
as well as guidance to implementers to make them want to adopt it
- Messages are valid while being edited (such as when the open or close isolate has been
inserted but the corresponding opposite isolate hasn't been entered yet)

**Cons**
- Requires additional effort to maintain the grammar
Expand Down
4 changes: 3 additions & 1 deletion exploration/expression-attributes.md
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
# Expression Attributes

Status: **Proposed**
Status: **Accepted**

<details>
<summary>Metadata</summary>
Expand All @@ -15,6 +15,8 @@ Status: **Proposed**
<dd><a href="https://github.com/unicode-org/message-format-wg/pull/772">#772</a></dd>
<dd><a href="https://github.com/unicode-org/message-format-wg/pull/780">#780</a></dd>
<dd><a href="https://github.com/unicode-org/message-format-wg/pull/792">#792</a></dd>
<dd><a href="https://github.com/unicode-org/message-format-wg/pull/845">#845</a></dd>
<dd><a href="https://github.com/unicode-org/message-format-wg/pull/846">#846</a></dd>
</dl>
</details>

Expand Down
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