The description of Responses object (for both fixed and patterned fields) reads:

A Reference Object can link to a response that the OpenAPI Object's components/responses section defines.

The use of the word "can" is particularly misleading here. Does this mean MAY or MUST?
That is, can any reference object be used, or is this implying a constraint that the reference object has to be of the form #/components/responses when used in a responses object?