By default, the flow keys are: Source IP address, destination IP address, source port, destination port, layer 3 protocol type, ToS byte (DSCP) and input interface. On Cisco Catalyst we speak of the flow mask that define the flow keys.

Full Interface
VLAN	source IP address	destination IP address	L3 protocol	source port	destination port
Full
VLAN	source IP address	destination IP address	L3 protocol	source port	destination port
Destination-Source-Interface
VLAN	source IP address	destination IP address	L3 protocol	source port	destination port
Source-Only
VLAN	source IP address	destination IP address	L3 protocol	source port	destination port
Destination-Only
VLAN	source IP address	destination IP address	L3 protocol	source port	destination port
Destination-Source
VLAN	source IP address	destination IP address	L3 protocol	source port	destination port