Hello PJMW,
I am not a CAIPS expert, but am willing to help u a bit!
I think CTG has no specific meaning, it can be a section or initials of an officer within VO to review your file on the mentioned date!
I guess the medicals could be sent to u after this date! This is just my opinion, could be wrong!
Btw what updated docs have you sent in March?
Good luck!
Swan