DAMA (Demand Assigned Multiple Access) is based on Detlef J. Schmidt DK4EG's suggestion. It is very commonly used by digitpeaters in Germany, Austria and Switzerland as it can reduce the rate of packet collisions significantly resulting in better, more reliable performance.
Linux implements DAMA slave support but not DAMA master mode. DAMA support is a kernel build option and needs to be explicitly enabled for each interface after bootup, for example to set interface sp0 to DAMA slave mode:
sysctl -w net.ax25.sp0.protocol=2
Setting this variable to 3 would choose DAMA master mode, but as said above this is currently not implemented. 0 is the good old simplex non-DAMA mode and 1 stands for duplex, non-DAMA operation. In addition the DAMA slave timeout needs to be configured:
sysctl -w net.ax25.sp0.dama_slave_timeout=<timeout>
The <timeout> value is given in 1/10th seconds.