Eemeli Aro

@macchiati The use case we're trying to solve for here are messages for which the units are not known until formatting time; for example something like: ``` The destination is...

Ah! The context I was missing was that "quantity" means a [specific thing](https://www.unicode.org/reports/tr35/tr35-75/tr35-info.html#quantities-and-base-units) here, and that it's not e.g. an attribute of a Measure object when one is used as...

Based on unicode-org/icu4x#6535 and other docs linked above, it looks like ICU4X is using "category" as a synonym for the CLDR "quantity". I don't see "quantity" with this meaning anywhere...

I don't really see what the user benefit might be of needing to explicitly opt-in to extensions that are supported by the formatter. Isn't that information equally well conveyed in...

@sffc Do you mean including such a validator somehow in the spec, or just having it exist in general, possibly even outside Unicode? I'm in the middle of refactoring Mozilla's...

I went through the spec, and the following are the potentially testable OPTIONAL or RECOMMENDED features for implementations and function handlers that I could find: ## Options for Implementations Implementations...

@gibson042 Do you mean that we ought to tighten further the paragraph recently added to the [Implementation Dependencies](https://tc39.es/ecma402/#sec-implementation-dependencies) section? > In browser implementations the initial set of locales, currencies, calendars,...

We currently say this about the `u:` options: https://github.com/unicode-org/message-format-wg/blob/a5eb9a395d34ddc0c25d129e63d2db810bc9b30b/spec/u-namespace.md?plain=1#L15-L16 Given that e.g. a conformant ICU4X implementation is therefore not required to implement them, are you ok with the spec still...

The option was extensively discussed in the WG through the [Expression Attributes](https://github.com/unicode-org/message-format-wg/blob/main/exploration/expression-attributes.md) design doc, which hopefully provides some of the rationalization that you're looking for. Note that its Metadata section...

I just realised that this whole discussion is also related to https://github.com/unicode-org/message-format-wg/pull/1015#pullrequestreview-2621386507, which we probably ought to address as well. In other words, as we currently don't have `:number notation`,...