The CCI-550 has a configurable number of AXI4 master interfaces. The suffix is My, where y is 0-6, depending on the configuration.
My
y
0-6
A.9.1 Write address channel signals.
A.9.2 Write data channel signals.
A.9.3 Write data response channel signals.
A.9.4 Read address channel signals.
A.9.5 Read data channel signals.
A.9.6 QoS signals.