Some Confusion about constructing M1/M2

[Mumunn]

Hi, I learned from the DSP0274_1.1.0 Spec that the Responder needs to use M1 to generate the signature when 

processing the Challenge Request, M1/M2 = Concatenate(A,B,C).
What puzzles me is whether it is possible for the Requester to send a request repeatedly? I did not find a note
about this in DSP0274_1.1.0 Spec. For example, is the Requester can send another Get Capabilities Request
after receiving a successful Capabilities Response? Is the Requester can send another Get Digests Request after
receiving a successful Digests Response?
And I noticed that he Concatenate rule of DSP0274_1.1.0 Spec: "If a response contains ErrorCode=ResponseNotReady:
Concatenation function is performed on the contents of both the original request and response", has one less word "successful"
than DSP0274_1.2.0 Spec. Does that mean that if I'm using DSP0274_1.1.0, I need to concatenate all RESPOND_IF_READY
request and ResponseNotReady response when constructing M1/M2?