axi read transfers

Can you explain what "Aciform" is so that I can see how these terms are being used ?

I would think that the term "overlapping" could mean that the AXI master could issue a read address for a second transactions while the read data transfers for the first transaction are still being returned, so that the new read address transfer "overlaps" the previous transfer read data transfers.

Whereas "out of order" would usually mean that if a master has issues 2 read transaction requests using different IDs, the read data for the second transaction could be returned before the read data for the first transaction, and the second issued transaction could then compete before the first issued transaction, hence "out of order". The 2 read transactions need to use different IDs for this to occur.