Ancient repeat sign

[Dan Eble]

https://www.pinterest.ca/pin/560909328587237881/

The sections of this work seem to be separated with a kind of repeat sign.

    A  :|||:  B  :|||:  C  :||:  D  :|:

Q. Do I understand correctly that this is performed AAA BBB CCD?

Q. Is this the most obvious way to code it?

    {
      \repeat volta 3 \A
      \repeat volta 3 \B
      \repeat volta 2 \C
      \repeat volta 1 \D
    }

Q. Is "signum repetitionis" an appropriate name for one instance of these signs?

Q. If LilyPond supported engraving these signs, which ancient staff contexts 
should enable it by default?  PetrucciStaff should, judging from what I see in 
Harmonice Musices Odhecaton.  I'm not sure about the others.

Q. Is there anything else that I should have asked?

Thanks,
--
Dan