Guide to Designing Resources: https://confluence.hl7.org/pages/viewpage.action?pageId=35718826#GuidetoDesigningResources-NamingRules&Guidelines

Rules

• Names for operations, resources and resource elements must:
  • be lowerCamelCase for elements, UpperCamelCase for resources, be lowercase for operations 

The #translate parameter name targetsystem is not lowerCamelCase and should be renamed to targetSystem

Guidelines

Names should:

• use different names for different elements within the hierarchy unless the semantic is the same in different context.

• • E.g. using “.name” for “sponsor.name” and “contact.name” is ok if the meaning of “name” is consistent for both sponsor and name.
• be sufficiently different from other names in the same space (other elements in same resource, other resources for a resource, other operations for an operation) to avoid confusion in verbal communication (“update” and “updates” is bad)

ConceptMap.source refers to a ValueSet (uri), ConceptMap.group.source refers to a CodeSystem (uri), the $translate output parameter match.source (uri) refers to a ConceptMap.

Similarly, ConceptMap.target and ConceptMap.group.target refer to a ValueSet and a CodeSystem respectively.

I suggest that:

• ConceptMap.source }}be renamed {{ConceptMap.inputScope
• ConceptMap.target }}be renamed {{ConceptMap.outputScope
• {{$translate }}has its corresponding parameters also renamed to match
• $translate's output parameter match.source is renamed to match.origin

We have had a lot of trouble being understood using the word "source" during verbal communication about ConceptMap. Additionally, we've had people complain that their ConceptMap doesn't "work" when they've specified ConceptMap.source as the CodeSystem URI and left ConceptMap.group.source blank because they've not read the spec. closely enough.