Clarification on the sparse fieldset response

Assuming the response document in the original question and the following

Does this mean that as soon as you explicitly request a restricted set of fields using fields[type] you must include the relationships for this type in the fields list, otherwise they will be excluded even if they are listed in the include parameter?

In other words if type people had first_name and last_name as attributes and comments as a relationship, then omitting the fields[people] request parameter would automatically mean that it is interpreted as being fields[people]=first_name,last_name,comments?

So adding fields[people]=first_name,last_name,comments to the URI or leaving it off has the same result?