What does “support” entail? Whether “we print its friendly name on the invoice before its value” or “we validate it, fetch the business data from the national r

What does “support” entail? Whether “we print its friendly name on the invoice before its value” or “we validate it, fetch the business data from the national registries and auto-fill the rest of the form”, you still need some special handling and registration. In that case, you don’t save much by using an existing scheme, and you there is a bigger risk of someone providing a schema you don’t support.