Expert System - Australian Flags by McGoo Software

Based on the responses you have made:

The flag is probably the Australian Naval Ensign

Conclusion Notes:

The Naval Ensign is a white ensign version of the Australian National Flag, for use by official Government naval defence forces (i.e. the Royal Australian Navy) and on RAN on-shore establishments. From the time the Royal Australian Navy was formed in 1911 until 1967, all its ships flew the White Ensign of the UK, i.e. the Royal Navy Ensign. In March 1967, the Holt Government adopted a new design, one consistent with the design of the other two Australian Flags but with a white field. This change was made at the request of the British Government which was concerned about the possibility of attacks on Royal Navy vessels near Vietnam, though the United Kingdom was not involved in the Vietnam War.

Expert System Rule:

IF on the flag the Southern Cross is visible
AND on the flag there is a Union Jack present
AND the field of the flag is white
THEN the flag is probably the Australian Naval Ensign.

Calculated Certainty Factor: 0.61 = probably