Unspecified enumeration of accepted values for template properties

[kezike]

For workflow.credentialTemplates and workflow.steps[stepName].stepTemplate, what is the complete range of values for type? I am aware that jsonata has been used in some implementations, but I don’t see this or a comprehensive range documented anywhere in the specification. Is there a plan to specify this?

[dlongley]

@kezike,

I don't think we would specify a complete range of values for type; it is essentially an extension point. As you noted, implementations are already using jsonata as an identifier for one template type -- but others could be used as well and the spec wouldn't limit this. The spec might suggest one or more options, but recommending or requiring support for at least one template language would require a normative reference in a W3C spec, something that might not be easily done with template languages.

[kezike]

@dlongley

OK, in that case, how do you envision that an extension would be advertised/published for VC API extensions? That's typically done through contexts, but I have not seen much on this process for VC API.

[msporny]

The group discussed this on the 2025-02-18 telecon. @dlongley noted that we might want to leave the identifier space open as an extension field for template languages, we could try to define a few: handlebars, mustache, jsonata, etc. The group didn't have a strong preference on templating language but did note that what we're looking for here is a JSON templating language.

A PR should be raised in the specification with a jsonata example, noting that jsonata is not the only option and the choice of templating languages is implementation specific.