What does app_trace_log do? (DM_LOG, DM_ERR, DM_DUMP and more)

Question

The function dm_ble_evt_handler has codes like this. 
 void dm_ble_evt_handler(ble_evt_t * p_ble_evt){ // from device_manager_peripheral.c
 
 
 switch (p_ble_evt->header.evt_id)
 { // neglecting other parts...
 case BLE_GAP_EVT_DISCONNECTED:
 //Disconnection could be peer or self initiated hence disconnecting and connecting
 //both states are permitted, however, connection handle must be known.
 DM_LOG("[DM]: Disconnect Reason 0x%04X
",
 p_ble_evt->evt.gap_evt.params.disconnected.reason);
 
 m_connection_table[index].state &= (~STATE_CONNECTED);
 
 }
}
 
 What does the DM_LOG Macro do? Where does this string is shown?

Petter Myhre · Accepted Answer

If you define ENABLE_DEBUG_LOG_SUPPORT in Options for Target->C/C++->Define, the "string" will be sent over UART. Then you can see it in a terminal like putty or termite. 
 The UART should be set up as in app_trace_init() .