Add support for language literals.
To ease adding metadata to documents, we need to add a SURF/TURF literal for a command resource type: a human language (like a Java locale). The type would be urf-Language and the canonical lexical form would be a language tag as per BCP 47. In SURF/TURF the delimiter would be ~, bringing to mind an audio waveform for spoken language.
Examples would include:
Thus ~en-US in a SURF/TURF document would be equivalent to |"en-us"|*urf-Language in a TURF document.
We need to think about defining an info-lang property. There are several "info" properties that need to be defined, such as info-description, and the https://urf.name/info/ namespace needs to be reserved. These would allow a general way to describe general things (sort of like Dublin Core, but built into the framework). From experience, it proves confusing to users if this were in the https://urf.name/urf/ namespace (e.g. urf-lang), as it might seem that the properties were for URF-specific things and not general descriptive properties. Update: The ticket for this is now URF-82.