[#228] Add scenario reference for messages, groups, components, and code sets

[kleihan]

Fixes #228

[erakadjiev]

Hello @kleihan

I saw that in a follow-up PR you've removed the documentation about the default value of scenarioRefId.

Additionally, the use="required" attribute of scenarioRefId should be removed too, in my opinion. I guess it's just an oversight, because the documentation above already says that "There are no defaults as scenario references are optional."

Otherwise, if we would leave scenarioRefId to be required, then every message, component, group, and code set would need to specify a scenario reference, which would break backwards compatibility and would lead to undefined behavior for base scenarios (they'd probably need to reference themselves as their parent). So I would be against introducing this new attribute if it's required.

[kleihan]

Hi @erakadjiev,

thank you for pointing this out, it is an error in the design. You are right and the intention is not to make the reference required. Scenarios without references should still be perfectly valid in v1.1. The intention was to require the ID if and only if a reference is being used. I guess this cannot easily be enforced by the schema and should therefore be clearly defined in the spec. I will enter new pull requests for the schema and the spec to correct this.

[erakadjiev]

Thank you, @kleihan! Yes, since scenarioRefId is the the reference itself, this cannot be expressed in the schema. In XSD 1.1 it could be expressed that scenarioRef can be present only if scenarioRefId is present. However, I think it cannot be done in XSD 1.0 (which Orchestra is using).